soft-finned fish vs malacopterygian

soft-finned fish and malacopterygian both are nouns.

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

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

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

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