Billiards is a traditional tabletop game played with balls, sticks called cues and a specialized table. Pool is a common nickname for the game pocket billiards. These two games use similar hardware but are different due to the objectives of each game and the number of balls used.
Pool and billiards are two versions of the same game. Each of these sports focuses on the idea of hitting small balls with the end of a narrow stick called a cue with the object being to accrue more points than the opponent.
It is most common in traditional billiards to use only three balls. All of the sides, or rails, of the table are bound in cushions and no pockets are present. The goal is the strike one ball and bounce it off the sides, hitting the other two on the rebound.
Pool is a common name for pocket billiards and is found in many American sports bars and recreational halls. It features a table the same size as a billiards table but with less cushioning on the rails and pockets set at the corners and midpoints of the longer edges. There are 18 balls in this game and one white cue ball, which is the only ball the cue ever contacts. Winning requires putting more balls into pockets or completing a colored set before the opponent.