I am very comfortable with American English, but when I was reading a very legal and technical European English paper, I had to admit that I was confused with their terminology and I was put in a very uncomfortable position of making assumptions of what the documents were alluding to. My responses to the paper in European English was of course in American English, which confused my European counterparts even more so because they found the context to be inconsistent with theirs. In the end, I had to be humble and ask for a thorough explanation, and I'm glad I did! I can't cite any specific examples, but some words have very different meanings in Europe than it does in America.