rooms vs apartment

rooms and apartment both are nouns.

Word	Noun	Adjective	Verb	Adverb
rooms	Yes	No	No	No
apartment	Yes	No	No	No

As nouns, apartment is a hypernym of rooms; that is, apartment is a word with a broader meaning than rooms:

rooms: apartment consisting of a series of connected rooms used as a living unit (as in a hotel)
apartment: a suite of rooms usually on one floor of an apartment house

Other hypernyms of rooms include flat.

rooms (noun)	apartment (noun)
apartment consisting of a series of connected rooms used as a living unit (as in a hotel)	a suite of rooms usually on one floor of an apartment house