furnace vs incinerator

furnace and incinerator both are nouns.

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

As nouns, incinerator is a hyponym of furnace; that is, incinerator 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.
incinerator: a furnace for incinerating (especially to dispose of refuse)

furnace (noun)	incinerator (noun)
an enclosed chamber in which heat is produced to heat buildings, destroy refuse, smelt or refine ores, etc.	a furnace for incinerating (especially to dispose of refuse)