Comparison of American football and rugby union possession of the ball at their own 20-yard (25 yard line in College Football) 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 conceding the score kicks off (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
American football in the United States encourage higher scoring and accommodate a smaller field of play. Some players that do not make the NFL play in indoor leagues or go to Canada and play in the Canadian Football League, which operates professionally on a somewhat older rule system with a number of differences from the American game but still recognizable as "football" to the casual American football observer. The CFL allocates half of its teams' rosters for players born and raised in Canada but allows the rest of the players to be foreign born (in practice, these spots are almost always filled by Americans); the CFL