The differences between American English and British English have always been of interest to me, partly I suppose because I watch so much American television.
One difference that is obvious to those who have been to both countries is the use of ‘main street’ and ‘high street’. Both mean the same thing – they refer to the principal road in a town, but whilst ‘main street’ is American English, ‘high street’ is preferred by British English.
There’s an interesting exploration of the origins of both terms over at Word Origins; here’s a short excerpt from the article:
Both main and high trace back to Old English, but their relevant adjectival uses are somewhat more recent. Main comes from the Old English noun mægn, meaning “physical strength, power,” and it has been used adjectivally to mean “principal, chief” since c. 1400. The Old English adjective heah, “tall, lofty, exalted,” could only signify “principal” when used in compounds; heahburh, for example, means “principal or capital city.” According to the Oxford English Dictionary, as a standalone adjective, high developed a sense of “principal” in Middle English, but this sense faded out and ceased to be productive in the seventeenth century, just as streets in the New World were beginning to be named.