wash room vs men's

wash room and men's both are nouns.

Word	Noun	Adjective	Verb	Adverb
wash room	Yes	No	No	No
men's	Yes	No	No	No

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

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

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