apartment vs maisonette

apartment and maisonette both are nouns.

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

As nouns, maisonette is a hyponym of apartment; that is, maisonette is a word with a more specific, narrower meaning than apartment:

apartment: a suite of rooms usually on one floor of an apartment house
maisonette: a self-contained apartment (usually on two floors) in a larger house and with its own entrance from the outside

apartment (noun)	maisonette (noun)
a suite of rooms usually on one floor of an apartment house	a small house
	a self-contained apartment (usually on two floors) in a larger house and with its own entrance from the outside