Sportscaster is also a primarily American English term for sportsreader — someone who reads sports news.
Sportscasters can be defined into two narrow categories. Play-by-play announcers are the primary speakers, valued for their articulateness and ability to describe the events of an often fast-moving event. Color commentators are valued for experience and insight into the game, and are often asked questions by the play-by-play announcer to give them a topic for analysis. The latter most often have gained their experience in the sport as a player and/or coach, while the former is more likely to be a professional broadcast journalist than a participant in the sport, although there are numerous exceptions to these general trends.
The most common format for a television broadcast is to have one of each type. An example is NBC Sunday Night Football, which is called by John Madden, a former head coach, and Al Michaels, a professional announcer.
Another difference between the two types is that color commentators will almost always announce only the sport they come from, while play-by-play announcers - such as Michaels, Howard David, and Mike Patrick - may have careers in which they call several different sports at one time or another. However, Brad Daugherty, a former professional basketball player, currently appears on coverage of NASCAR auto racing on ESPN.
Although the combination of a play-by-play announcer and one or more color commentators is standard today, in the past it was much more common for a play-by-play announcer to work alone. Vin Scully, longtime announcer for the Brooklyn/Los Angeles Dodgers baseball team, is one of few examples of this practice still existing today.