shaft furnace vs furnace

shaft furnace and furnace both are nouns.

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

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

shaft furnace: a furnace in the form of a vertical cylinder in which hot gas is forced upwards through the contained solids.
furnace: an enclosed chamber in which heat is produced to heat buildings, destroy refuse, smelt or refine ores, etc.

shaft furnace (noun)	furnace (noun)
a furnace in the form of a vertical cylinder in which hot gas is forced upwards through the contained solids.	an enclosed chamber in which heat is produced to heat buildings, destroy refuse, smelt or refine ores, etc.