cartilaginous fish vs chondrichthian

cartilaginous fish and chondrichthian both are nouns.

Word	Noun	Adjective	Verb	Adverb
cartilaginous fish	Yes	No	No	No
chondrichthian	Yes	No	No	No

As nouns, cartilaginous fish and chondrichthian are synonyms defined as:

cartilaginous fish and chondrichthian: fishes in which the skeleton may be calcified but not ossified

cartilaginous fish (noun)	chondrichthian (noun)
fishes in which the skeleton may be calcified but not ossified	fishes in which the skeleton may be calcified but not ossified