butterfish vs bracketed blenny

butterfish and bracketed blenny both are nouns.

Word	Noun	Adjective	Verb	Adverb
butterfish	Yes	No	No	No
bracketed blenny	Yes	No	No	No

As nouns, bracketed blenny is a hypernym of butterfish; that is, bracketed blenny is a word with a broader meaning than butterfish:

butterfish: slippery scaleless food fish of the northern Atlantic coastal waters
bracketed blenny: small eellike fishes common in shallow waters of the northern Atlantic

Other hypernyms of butterfish include gunnel.

butterfish (noun)	bracketed blenny (noun)
small marine fish with a short compressed body and feeble spines	small eellike fishes common in shallow waters of the northern Atlantic
slippery scaleless food fish of the northern Atlantic coastal waters
any of numerous small flat Atlantic food fish having smooth skin