American English is spoken more carelessly, and more from the throat, while British English is more proper(well, in London in it, not so much in the country), and they "round" their words more. They would say "hello" like "hellauw" Americans you the word "like" way too many times in a sentence and also use idimatic expressions that make it hard for non-native speakers to understand. Here is a sentence an american might say: "Betty! Like Oh my God! Sherry just bombed the math test and started to cry." Yeah, that's not the best example but i hope it helps!