columbarium vs birdhouse

columbarium and birdhouse both are nouns.

Word	Noun	Adjective	Verb	Adverb
columbarium	Yes	No	No	No
birdhouse	Yes	No	No	No

As nouns, birdhouse is a hypernym of columbarium; that is, birdhouse is a word with a broader meaning than columbarium:

columbarium (noun)	birdhouse (noun)
a sepulchral vault or other structure having recesses in the walls to receive cinerary urns	a shelter for birds
a niche for a funeral urn containing the ashes of the cremated dead
a birdhouse for pigeons