Most just call it NFL to avoid confusion
I usually hear it referred to as football, so I've adapted to associate that with American football. One adapts to the colonials ways. LOL
Yes, though granted, it isn't difficult to do -- at least in the UK, where people go completely insane at games, and where team support reaches ridiculous heights (accidentally wearing a team's colors can cause a riot, for example). I don't see the same level of insanity here in the US.
Insane isn't even the word for it. You guys go absolutely out of your minds for your football (ahem...soccer ).
We enjoy our football (or pointy-ended-oblong-you-can-carry-with-your-hands-ball), and a few people love it just a little too much, but the level of darn near national pride doesn't exist here for our football. Heck, baseball doesn't even get that type of enthusiasm, and that's supposed to be "America's Sport" and our "National Pastime."
Actually, that is starting to change.
Not sure you remember the incident between the Dodger and Giants fan in 2011: San Francisco Giants Fan in Coma After Being Attacked by L.A. Dodgers Fans. Similar incidents starting across all sport here.
The funny thing is how we're just starting to get the violence, and Brits are just having to get used to the "moneyball" that we've had since the early 70's. And not just the UK - Europe in general. Neymar's transfer fee from Barca to PSG was disgusting.
I've always thought fans of American football were a lot more sedate, but it seems they're starting to catch up to the UK.
ETA: kind of off-topic now, but here's John Cleese discussing football vs soccer.