Whats it like being an american?

some americans wonder what it's like to live in uk and some british people like myself wonder what it's like to live in the us, I mean america has so many jobs I'm sure and they have so many cool cities, I live in belfast the capital of northern ireland, there's probably towns in america that are bigger, the only city that actually has just about skyscrs in the uk is london obviously. But I wanna know what are the benefits off being american opposed to being a briton, what are green cards, what are social security numbers. The only thing I'm not comfortably about doing is the selective service, I'm afraid sometime in the future they might bring it back and I'll have to go to war, you never know, it could happen! so are the benefits of living in the us