Bahahahaha you guys have to wear helmets and shoulder pads to play football. AND have a seperate team for offense and defence!!! bahahaha the defensive teams are just fatties, that need a rest when the offensive starts. LOL! :lol:
Separate players for offense and defence. Not separate teams.
Oh, are there some that play in both?
A football "team" is one organization. This organization is separated into smaller groups, which play different positions, which is separated into sub-categories (offense, defence, and special teams). It's like the army; you've got riflemen, snipers, demolition experts and minesweepers, but they're all a part of one army.
In smaller forms of the sport (ones that aren't in mass media) you can see people playing on both offense and defence.