I'm British. I remember teaching English in Spain 20 years ago and having to get my American girlfriend at the time to explain "twenty of six" to me, which was in all the teaching books we were using.
On a side note one expression I find odd in American English is 'off of' as in 'get off of me' instead of 'get off me' which Jim Butcher uses a lot in The Dresden Files. I assume it's colloquial.
Also something I first spotted in Janet Evanovich's books, and I'm now seeing everywhere is: 'a couple million dollars' or 'a couple bullets' instead 'a couple
of million dollars' or 'a couple
of bullets'. That seems a bit odd to me.
Bill Bryson has a lot to say about the differences between British and American English in the book Mother Tongue, and from what I can remember, his conclusion was that when these differences show up a lot of the time it's because American English tends to use old fashioned words or expressions or grammar forms that have fallen out of favour in British English.
And yes, I spelt favour right, and the irregular past tense of spell come to that, whatever Noah Webster's committee had to say on the matter.
