restroom vs men's

restroom and men's both are nouns.

Word	Noun	Adjective	Verb	Adverb
restroom	Yes	No	No	No
men's	Yes	No	No	No

As nouns, men's is a hyponym of restroom; that is, men's is a word with a more specific, narrower meaning than restroom:

Other hyponyms of restroom include ladies' room, powder room, latrine, men's room.

restroom (noun)	men's (noun)
a toilet that is available to the public	a public toilet for men