finback vs rorqual

finback and rorqual both are nouns.

Word	Noun	Adjective	Verb	Adverb
finback	Yes	No	No	No
rorqual	Yes	No	No	No

As nouns, rorqual is a hypernym of finback; that is, rorqual is a word with a broader meaning than finback:

finback: large flat-headed whalebone whale having deep furrows along the throat; of Atlantic and Pacific
rorqual: any of several baleen whales of the family Balaenopteridae having longitudinal grooves on the throat and a small pointed dorsal fin

Other hypernyms of finback include razorback.

finback (noun)	rorqual (noun)
large flat-headed whalebone whale having deep furrows along the throat; of Atlantic and Pacific	any of several baleen whales of the family Balaenopteridae having longitudinal grooves on the throat and a small pointed dorsal fin