bell-type furnace vs furnace

bell-type furnace and furnace both are nouns.

Word	Noun	Adjective	Verb	Adverb
bell-type furnace	Yes	No	No	No
furnace	Yes	No	No	No

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

bell-type furnace: a furnace used for removing the strain hardening in the steel strip as an alternative to continuous annealing.
furnace: an enclosed chamber in which heat is produced to heat buildings, destroy refuse, smelt or refine ores, etc.

bell-type furnace (noun)	furnace (noun)
a furnace used for removing the strain hardening in the steel strip as an alternative to continuous annealing.	an enclosed chamber in which heat is produced to heat buildings, destroy refuse, smelt or refine ores, etc.