Rachycentridae vs fish family

Rachycentridae and fish family both are nouns.

Word	Noun	Adjective	Verb	Adverb
Rachycentridae	Yes	No	No	No
fish family	Yes	No	No	No

As nouns, fish family is a hypernym of Rachycentridae; that is, fish family is a word with a broader meaning than Rachycentridae:

Rachycentridae (noun)	fish family (noun)
family of pelagic fishes containing solely the cobia	any of various families of fish