percoidean vs spiny-finned fish

percoidean and spiny-finned fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
percoidean	Yes	No	No	No
spiny-finned fish	Yes	No	No	No

As nouns, spiny-finned fish is a hypernym of percoidean; that is, spiny-finned fish is a word with a broader meaning than percoidean:

percoidean: any of numerous spiny-finned fishes of the order Perciformes
spiny-finned fish: a teleost fish with fins that are supported by sharp inflexible rays

Other hypernyms of percoidean include acanthopterygian.

percoidean (noun)	spiny-finned fish (noun)
any of numerous spiny-finned fishes of the order Perciformes	a teleost fish with fins that are supported by sharp inflexible rays