scombroid fish vs percoidean

scombroid fish and percoidean both are nouns.

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

As nouns, percoidean is a hypernym of scombroid fish; that is, percoidean 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
percoidean: any of numerous spiny-finned fishes of the order Perciformes

Other hypernyms of scombroid fish include percoid, percoid fish.

scombroid fish (noun)	percoidean (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