If you remember one thing about clothing word differences in England, remember this: It's not pants, it's trousers!!!
If you say "pants" to a Brit, they think underwear, because that's what the word "pants" means over here. Therefore, statements by innocent Americans such as, "If I'd known how warm it was going to be outside today, I wouldn't have worn pants under my dress," provide much fodder for amusement around here. This also explains why the now classic Wallace and Gromit film is called "The Wrong Trousers." Were it called "The Wrong Pants," the meaning would be very different, indeed.
Other differences between American English and British English (with the American usage put first):
tank top/undershirt = vest
vest = waistcoat
suspenders = braces
sweater = jumper
tennis shoes/sneakers = trainers
swimsuit/bathing suit = swimming costume/cozzie/swimming kit
onesie = baby grow
Hi Jennifer, thanks for the spelling correction. I've only ever seen it spelled "baby grow." However, the only place I've ever seen it written out is on a hand-lettered sign in a warehouse of donated clothing, so that would explain the error. (Keep in mind that since I am a volunteer living on a rapidly dwindling pile of dollars-to-be-converted, I pretty much avoid clothing stores since I can't buy anything anyway!)
A onesie is called a babygro not a baby grow! It can also be referred to as a romper suit, which is something else over here in the US too, just to confuse us Brits even more!