Are we talking about American football or association football/soccer? With American football, you can play it casually, but the rule changes you have to make

Are we talking about American football or association football/soccer? With American football, you can play it casually, but the rule changes you have to make in order for people not to get clobbered turn it into a very different game from what you see in a pro or college setting. (The level of working out aggression is different too.)