In American football, "play" is stopped when a player is ruled down or out of bounds, whereas the play in rugby union continues until a player or the ball goes out of bounds, a player/team commits a foul or a player scores. Net stoppages when including throw ins and kick exchange are comparable at all but the highest (televised) levels.
The forward pass and the stoppage when a player is grounded results in short plays and a generally staccato game play in American football, as opposed to the longer and more fluid passages of play found in rugby union.
In rugby, kicking during the flow of the game is done for tactical reasons (both offensive and defensive); if the ball is recovered by the kicking team, it can lead to significant improvement in field position. In American football, a team that kicks the ball during play automatically gives up possession and cannot recover the ball unless an error in catching the ball (aka "muff") is made by the receiving team; because of this, punting is typically done only when teams do not expect to be able to retain possession (i.e. on fourth down). Additionally, rule changes made in the early 20th Century mandated that field goals cannot be made in front of the line of scrimmage; this has led to the demise of the drop-kick field goal in American football.
The Football Association was formed in England in October 1863. Differences of opinion about the proposed laws led to the formation of the first governing body for rugby in 1871 the Rugby Football Union. Laws were drawn up for rugby football which was now distinct from Association football (soccer).
In 1872 rugby clubs were established in the San Francisco Bay Area, which were mainly comprised of British expatriates. The first recorded rugby match in the United States occurred on May 14, 1874 between Harvard University and McGill University.
In 1876, Yale, Harvard, Princeton, and Columbia formed the Intercollegiate Football Association, a competition based on the traditional rules of rugby. The sport of American football evolved from these intercollegiate games (see History of American football).
Back in England, a schism developed between those who favoured strict amateurism and those who felt that players should be compensated for time taken off work to play rugby. In 1895, this resulted in the formation of a break-away governing body, the Northern Union.
The Northern Union began to make changes to the laws of rugby in 1906, which resulted in the sport of rugby league. The Rugby Football Union's version of rugby became as known as rugby union after its governing body.
Additional lines differ markedly with American football fields marked at every 5 yard interval, whereas rugby union fields only have two further solid lines called the 22 metre lines and four broken lines each halving a half (resulting in four quarters and being translated as "quarter lines" in some languages). The dotted lines are made of two 10 metre lines on each side of the halfway line and two 5 metre lines before each goal line. Rugby union fields also have another set of dotted 5 metre lines.
The yard lines in American football are vitally important during game play, because a team's advance is measured against these lines, which in turn determines ball possession, whereas the halfway, 22 and 10 yards lines only determine the position of players during various rugby union kick-offs (which could be from the halfway line or 22s) or line-out in the case of the broken line 5 yd from the side lines.
The ball is put into play by a snap. All players line up facing each other at the line of scrimmage. One offensive player, the center, then passes (or "snaps") the ball between his legs to a teammate, usually the quarterback.
Players can then advance the ball in two ways:
A down ends, and the ball becomes dead, after any of the following:
Rugby union is based on the 'right to contest possession'. A team is not required to surrender possession when the ball carrier is tackled, in contrast to American football, where a team must surrender their possession when a player is tackled and no downs remain. Rugby union players must win possession in open play, unless the team in possession makes an infringement, scores, or the ball leaves the field of play.
A team in rugby union can advance the ball in two ways:
Possession may change in different ways in both games:
In both codes, tactical kicking is an important aspect of play. In American football, it is normal to punt on the last down, but as in rugby union a kick can take place at any phase of play.
In American football, the offense can throw the ball forward once on a play from behind the line of scrimmage. The forward pass is a distinguishing feature of American and Canadian football as it is strictly forbidden in rugby.
The ball can be thrown sideways or backwards without restriction in both games. In American football this is known as a lateral and is much less common than in rugby union.
In both codes, if the ball is caught by an opposition player this results in an interception and possession changes hands.
In both games it is permitted to bring down the player in possession of the ball and prevent them making forward progress. In rugby, unlike in American football, the ball is still in play. Players from either team can take possession of the ball. The tackled player must present the ball (release the ball) so that open play can continue.
Rugby union rules do not allow tackles above the plane of the shoulders. Only the player who has possession of the ball can be tackled. The arms of the attacker must also wrap around the player being tackled. If a maul or ruck is formed, a player may not "ram" into the formation without first binding to the players.
In American football, tacklers are not required to wrap their arms around the ball carrier before bringing him to the ground; in fact, the ball carrier is often "tackled" by the defender taking a running start and hitting the ball carrier to knock them to the ground. Tackles can also be made by grabbing the ball carrier's jersey and pulling him to the ground (though pulling down a ball carrier by the pads behind his neck is known as a "horse collar" and is illegal in the professional National Football League). If a ball carrier is stopped for more than a few seconds, the referee can blow the whistle, declare the player's forward progress stopped, and end the play even though the ball carrier is not actually tackled to the ground.
In American football, players are allowed to 'block' players without the ball, this is not permitted in rugby union and would be considered 'obstruction', resulting in a penalty.
A touchdown is the American equivalent of a try. Unlike American football, both codes of rugby require the ball to be grounded, whereas in American football it is sufficient for the ball to enter the end zone (in-goal area) when in the possession of a player (making the term "touchdown" a misnomer). In American football a touchdown scores 6 points; in rugby union a try is worth 5 points.
In both games, following a try / touchdown, there is the opportunity to score additional points by kicking the ball between the posts and over the bar. In American football this is called an extra point (worth 1 point); in rugby union it is known as a conversion (worth 2 points). (The result is that both the touchdown/extra point combination and the try/conversion combination, when successful, total to 7 points.) One key difference between an extra point and a conversion is that a conversion must be taken from a position in line with where the try was scored. Hence it is important to ground the ball under the posts rather than in the corner which makes for a difficult kick. Also, American football features the option of the going for a 2-point conversion, where the attacking team gets one chance from 3 yards out (2 in the NFL) to get the ball in the endzone again. This would be worth 2 points on top of the 6 already awarded for the touchdown.
In American football teams often opt to go for a field goal (worth 3 points) rather than attempt a touchdown. The rugby equivalent is a drop goal (worth 3 points in union and only one in league). The key difference between a field goal and a drop goal is that a field goal attempt is normally kicked with a team-mate holding the ball, whereas in rugby the ball must hit the ground and be kicked from a half-volley.
A similar concept in rugby is the penalty goal. Following the award of the penalty, the attacking team may opt to kick for goal rather than advance the ball by hand or punting. This scores 3 points. The penalty goal is similar to a field goal in American football in that the ball is kicked from the ground, but it cannot be charged. There is no direct equivalent to a penalty goal in American football. A rare play called a "fair catch kick" is analogous to a goal from mark which existed in rugby union at one time.
American football has one further method of scoring which does not exist in rugby. If the team with possession causes the ball to enter their own endzone, and the ball carrier is then tackled while within the endzone, then this results in a safety which scores 2 points for the attacking team and results in the defending team having to kick the ball to the team who recorded it. In rugby union this does not score any points but results in a scrum 5 meters from the try zone with the tackling team in possession.
If the ball is kicked past the try line and the receiving team grounds it without leaving the past the tryline a drop kick from the 22-meter line ensues In American football, if a kick-off or punt goes into the endzone and the receiving team downs it without leaving the endzone, the result is a "touch back" and the receiving team gains possession of the ball at their own 20-yard line.
An important difference between the two sports involves the aftermath of a score. In American football, the scoring team kicks off, except after a safety. In rugby union, the team scored upon kicks off. (However, in rugby sevens, a variant of rugby union featuring seven players per side, the scoring team kicks off.)
An American football team consists of an offensive unit, a defensive unit and a "special teams" unit (involved in kicking and kick returns). Only eleven players can be on the field at any time. Players are allowed to play on more than one of the units, this is the norm for all but the highest levels of play (professional and large schools). The kicking unit, with the exception of a few specialists, will usually be made up of reserve players from the offense and defense.
In both kinds of rugby the same players have to both defend and attack. There are fifteen players in a rugby union team (except in sevens and tens). Many of the positions have similar names but in practice are very different. A fullback in American football is very different from a fullback in rugby. Some of the positions are fairly similar; a fly-half carries out a similar role to a quarterback in American football; however, American quarterbacks touch the ball on every offensive play.
Because of the playing time, number of pauses, number of players and the nature of the game in general rugby players will typically need higher physical endurance than American football players while more short-term bursts of physical strength, power, and speed will be required in American football (amongst equivalent positions and weights). Collisions between players in rugby union tend to last significantly longer than American football, in which collisions are more often "hits" in which the momentum of the player is enough to bring the other player to ground or at least forcing an error or fumble. In rugby union, hits are also a valid way of tackling, providing at least an appearance of attempting to bind is made. These hits are not usually at the speed of American football both because of the nature of the game and the lack of protective equipment. Additionally, rugby offsides rules and the lack of a forward pass significantly reduce the chance of a player receiving a "blind-side" hit (i.e. being hit and/or tackled from behind). In American football, players receiving a forward pass are often extremely vulnerable because they must concentrate on catching the ball, often jumping very high or stretching out and thereby exposing their body to punishing hits; in rugby a similar situation exists when a ball is kicked in the air (kicks can go forward in rugby), again leaving the player's focus on catching the ball rather than seeing an imminent hit, usually in rugby ball carriers can anticipate a hit and can brace themselves accordingly.
During rugby, the contact times between players are usually much longer, as a more wrestling approach is required to bring players down, as momentum can not always be relied upon particularly when the lines between the teams are consistently close, not allowing for significant momentum to be developed before meeting a defender. This increased contact time can result in mauls, in which players have to attempt to push the other player back. In American football equivalents to mauls are virtually non existent, as play stops when the ball is stopped. In rugby union no such stoppage occurs, and the open ball may be contested by mauls of several players. These difference can be summed up in the idea that in American football the objective is to bring the player to ground or to disrupt a pass to end the play, whereas in rugby the main objective is to stop the player from breaking the line, therefore mauling and rucking will sometimes occur when bringing a player down is not possible.
American football quarterbacks -- and increasingly, their coach -- have the ability to decide what the next play would be in many occasions during the game, thus allowing for both complex tactics displayed within individual plays and overall game-wide strategy in play calling and play selection. In rugby union, the continuous nature of the game implies that there is no time to discuss team strategy, therefore offensive actions may seem to lack a definite direction for some periods of time. Rugby is more movement based than American football in which short bursts are needed.
Rugby players often continue to participate in the game long after they have left school. In America, amateurs who have left school rarely play full tackle football, but often play touch football or flag football.
Rugby union players are allowed to wear modest padding on the head, shoulders and collarbone, but it must be sufficiently light, thin and compressible to meet IRB standards. The headguard, also called a "scrum cap", is now commonly worn throughout all levels of the game. Protective headgear which is becoming essential because of the quantity of cuts and head injuries that can occur, particularly by the boots of players involved in rucking. Hard plastic or metal are prohibited in rugby kit. This includes hard plastic shin guards. No form of metal is allowed in any rugby kit, except for IRB-approved soft aluminum studs on boots. An essential part of the safety equipment needed for rugby is the gumshield or mouthguard. Players also have the option to use fingerless gloves which have been introduced recently to the game allowing players to better grip the ball.
American football players wear much bulkier protective equipment, such as a padded plastic helmet, shoulder pads, hip pads and knee pads. These protective pads were introduced decades ago and have improved ever since to help minimize lasting injury to players. An American football helmet consists of a hard plastic top with thick padding on the inside, a facemask made of one or more metal bars, and a chinstrap used to secure the helmet. An unintended consequence of all the safety equipment has resulted in increasing levels of violence in the game which unprotected would be extremely dangerous. In previous years with less padding, tackling more closely resembled tackles in rugby union, with less severe impacts and less severe structural injuries.