scombroid fish vs percoid

scombroid fish and percoid both are nouns.

Word	Noun	Adjective	Verb	Adverb
scombroid fish	Yes	No	No	No
percoid	Yes	No	No	No

As nouns, percoid is a hypernym of scombroid fish; that is, percoid is a word with a broader meaning than scombroid fish:

scombroid fish: important marine food and game fishes found in all tropical and temperate seas; some are at least partially endothermic and can thrive in colder waters
percoid: any of numerous spiny-finned fishes of the order Perciformes

Other hypernyms of scombroid fish include percoid fish, percoidean.

scombroid fish (noun)	percoid (noun)
important marine food and game fishes found in all tropical and temperate seas; some are at least partially endothermic and can thrive in colder waters	any of numerous spiny-finned fishes of the order Perciformes