American and British Vocabulary differences (Third “episode”)

It’s actually not that clear-cut (as it was for BE and AE terms in the first and second episode), but we can generally state that the American English term “apartment” corresponds to the British English word “flat”. The exact meaning of the word apartment depends on where you live.
For example, in large parts of Canada and in or near New York City, it is used for a residence in a multi-unit building; this meaning is the one given by Oxford Advanced Learner’s Dictionary, and is a synonym of the British word flat.
In most of the rest of the U.S. and on the West Coast of Canada, the word apartment is reserved for a rented residence in a multi-unit building; if the residences in the building are individually owned, they are called condos.