butterfish vs driftfish

butterfish and driftfish both are nouns.

Word	Noun	Adjective	Verb	Adverb
butterfish	Yes	No	No	No
driftfish	Yes	No	No	No

As nouns, driftfish is a hyponym of butterfish; that is, driftfish is a word with a more specific, narrower meaning than butterfish:

butterfish: small marine fish with a short compressed body and feeble spines
driftfish: small (6 inches) tropical butterfishes found worldwide

butterfish (noun)	driftfish (noun)
small marine fish with a short compressed body and feeble spines	small (6 inches) tropical butterfishes found worldwide
slippery scaleless food fish of the northern Atlantic coastal waters	larger butterfishes of the western Atlantic from the New York area to the northern Gulf of Mexico
any of numerous small flat Atlantic food fish having smooth skin