Don't know about the USA, but in the UK there are two codes of Rugby - Rugby League (13 players) and Rugby Union (15 players). I mainly follow League (which is also big in Australia and to a lesser extent New Zealand and France). The team I'm a big fan of is Hull FC. At my age, being a fan is the only option, although I did play many years ago when I was a youth.

I much prefer Rugby to football (soccer) where they roll about in agony at the slightest touch.