malacopterygian vs soft-finned fish

malacopterygian and soft-finned fish both are nouns.

Word	Noun	Adjective	Verb	Adverb
malacopterygian	Yes	No	No	No
soft-finned fish	Yes	No	No	No

As nouns, malacopterygian and soft-finned fish are synonyms defined as:

malacopterygian and soft-finned fish: any fish of the superorder Malacopterygii

malacopterygian (noun)	soft-finned fish (noun)
any fish of the superorder Malacopterygii	any fish of the superorder Malacopterygii