finback whale vs rorqual

finback whale and rorqual both are nouns.

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

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

finback whale: 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 whale include razorback.

finback whale (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