The fundamental differences between BBUS and nearly all other BB's elsewhere is that 1: They're allowed to talk about nominations and form alliances. 2: They vote out their fellow houseguests entirely by themselves. These differences change the dynamic completely. Plus it's an American reality TV show, and this is edited in the way we have come to expect from American TV... totally different to ours.
You won't get nearly as much from the show if you don't look at the live feeds. Big Brother USA is all about the 'game', as far as the television episodes are edited. Most of what they put on the TV show is strategy between the houseguests, who are more like players.
Watching the live feed allows you to see what the houseguests are really like, although you will find that there's an awful lot of strategy and alliance-forming that goes on in general: The BBUSA contestants really want to win the money. It's RUTHLESS.
And you will find that the challenges and games set for the houseguests blow the BBUK ones out of the water, real tests of endurance and real big, over the top games that make ours look like an afterthought.