The list below highlights the difference between British English and American English.
Apart from the spelling differences - you can see those by clicking on the USA - UK differences at the left hand side of this page - there are a number of differences in vocabulary listed below.
I suggest you look them over because you never know when you may run into an American after studying British English, or when you may run into a Brit after having studied American English.
Having been to England a number of times now myself, I can assure you that the differences between American and British vocabulary are just enough to cause a few laughs.