I thought it would be fun (ok, maybe not fun..but interesting?) to start a thread on the differences incase i've missed some.
There is the obvious ones...
English: crisps. (Chips in England are fries.)
American: Movie theatre
English: Cinema or pictures
English: Fag (although that does have more than one meaning in both countries)
English: Mobile phone
English: Trainers (Irish: runners)
and so on.....
Pants in England are worn underneath your trousers, just like American panties. While the British may understand what you mean if you speak of 'my baggy pants,' they will likely find the mental image this conjures amusing.
The funniest one I find is American: fanny which means bum (i believe?) but fanny in English is the female reproductive organ. I still giggle when I hear American tourists talking about their fanny packs.
Anyone got any other weird or wondrous ones?