family Gavidae vs bird family

family Gavidae and bird family both are nouns.

Word	Noun	Adjective	Verb	Adverb
family Gavidae	Yes	No	No	No
bird family	Yes	No	No	No

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

family Gavidae: loon family
bird family: a family of warm-blooded egg-laying vertebrates characterized by feathers and forelimbs modified as wings

family Gavidae (noun)	bird family (noun)
loon family	a family of warm-blooded egg-laying vertebrates characterized by feathers and forelimbs modified as wings