public toilet vs men's

public toilet and men's both are nouns.

Word	Noun	Adjective	Verb	Adverb
public toilet	Yes	No	No	No
men's	Yes	No	No	No

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

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

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