snake mackerel vs gempylid

snake mackerel and gempylid both are nouns.

Word	Noun	Adjective	Verb	Adverb
snake mackerel	Yes	No	No	No
gempylid	Yes	No	No	No

As nouns, gempylid is a hypernym of snake mackerel; that is, gempylid is a word with a broader meaning than snake mackerel:

snake mackerel: predatory tropical fishes with jutting jaws and strong teeth
gempylid: snake mackerels; elongated marine fishes with oily flesh; resembles mackerels; found worldwide

snake mackerel (noun)	gempylid (noun)
predatory tropical fishes with jutting jaws and strong teeth	snake mackerels; elongated marine fishes with oily flesh; resembles mackerels; found worldwide