It's a bit more complicated than in the lists so far.
There are sandwiches called sandwiches in the UK, the only time I've heard called buttie is the bacon buttie which is a bacon roll, or chip buttie which is a yeah, lots of chips in a bread roll. It varies with regions and people though most likely.
Also pants in the UK is underwear so if you hear someone took off their pants you tend to go
Also saying somethings is pants is saying it's bad.
pants = trousers
underwear = pants
horny = randy
fanny pack* = bum bag
bill = note
There are more though.
*fanny means something completely different in British English so that word for a bum bag always makes me giggle.