furnace vs crematorium

furnace and crematorium both are nouns.

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

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

furnace: an enclosed chamber in which heat is produced to heat buildings, destroy refuse, smelt or refine ores, etc.
crematorium: a furnace where a corpse can be burned and reduced to ashes

furnace (noun)	crematorium (noun)
an enclosed chamber in which heat is produced to heat buildings, destroy refuse, smelt or refine ores, etc.	a furnace where a corpse can be burned and reduced to ashes
	a mortuary where corpses are cremated