A couple Americans have complained about UK spelling of words, so I'd guess there were no differences on that point. I have not heard any mention of other differences between the UK and US versions.
In the French version they changed some of the character names, but were not very thorough. For the thieves' guild first test, you are told to pickpocket an amulet from a drunk, but they only changed Sweney's name in one of the locations (dialog / character name). That may have been fixed in a patch.
