damselfish vs percoidean

damselfish and percoidean both are nouns.

Word	Noun	Adjective	Verb	Adverb
damselfish	Yes	No	No	No
percoidean	Yes	No	No	No

As nouns, percoidean is a hypernym of damselfish; that is, percoidean is a word with a broader meaning than damselfish:

Other hypernyms of damselfish include percoid, percoid fish.

damselfish (noun)	percoidean (noun)
small brilliantly colored tropical marine fishes of coral reefs	any of numerous spiny-finned fishes of the order Perciformes