family Alcidae vs bird family

family Alcidae and bird family both are nouns.

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

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

family Alcidae: web-footed diving seabirds of northern seas: auks, puffins, guillemots, murres, etc.
bird family: a family of warm-blooded egg-laying vertebrates characterized by feathers and forelimbs modified as wings

family Alcidae (noun)	bird family (noun)
web-footed diving seabirds of northern seas: auks, puffins, guillemots, murres, etc.	a family of warm-blooded egg-laying vertebrates characterized by feathers and forelimbs modified as wings