housing vs apartment

housing and apartment both are nouns.

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

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

housing (noun)	apartment (noun)
structures collectively in which people are housed	a suite of rooms usually on one floor of an apartment house
a protective cover designed to contain or support a mechanical component
stable gear consisting of a decorated covering for a horse, especially (formerly) for a warhorse