mortuary vs crematorium

mortuary and crematorium both are nouns.

Word	Noun	Adjective	Verb	Adverb
mortuary	Yes	Yes	No	No
crematorium	Yes	No	No	No

As nouns, crematorium is a hyponym of mortuary; that is, crematorium is a word with a more specific, narrower meaning than mortuary:

mortuary: a building (or room) where dead bodies are kept before burial or cremation
crematorium: a mortuary where corpses are cremated

mortuary (noun)	crematorium (noun)
a building (or room) where dead bodies are kept before burial or cremation	a furnace where a corpse can be burned and reduced to ashes
	a mortuary where corpses are cremated

mortuary (adjective)	crematorium (adjective)
of or relating to a funeral
of or relating to or characteristic of death