I remember Jean Redpath being funny about the fact that British and Americans use different words for things. Though not so many as you might think, here in Western PA. The local dialect includes a lot of Scots words. (We redd up, instead of clean up, and streets are slippy in the winter.) She seemed very unBritishly amused by our differences.

In the U.S. if you say, "It's in the boot," someone will explain, somewhat sheepishly, "Uh over here we call usually call it a trunk." In England if you say, "It's in the trunk." Someone will say sharply, "That's boot!" It's not what you say, it's the way that you say it.