family Xiphiidae vs fish family

family Xiphiidae and fish family both are nouns.

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

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

family Xiphiidae (noun)	fish family (noun)
comprising the common swordfishes	any of various families of fish