art gallery vs room

art gallery and room both are nouns.

Word	Noun	Adjective	Verb	Adverb
art gallery	Yes	No	No	No
room	Yes	No	Yes	No

As nouns, room is a hypernym of art gallery; that is, room is a word with a broader meaning than art gallery:

art gallery (noun)	room (noun)
a room or series of rooms where works of art are exhibited	an area within a building enclosed by walls and floor and ceiling
	the people who are present in a room
	space for movement
	opportunity for

art gallery (verb)	room (verb)
	live and take one's meals at or in