crematorium vs furnace

crematorium and furnace both are nouns.

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

As nouns, furnace is a hypernym of crematorium; that is, furnace is a word with a broader meaning than crematorium:

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

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