genus Zonotrichia vs bird genus

genus Zonotrichia and bird genus both are nouns.

Word	Noun	Adjective	Verb	Adverb
genus Zonotrichia	Yes	No	No	No
bird genus	Yes	No	No	No

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

genus Zonotrichia (noun)	bird genus (noun)
large New World sparrows	a genus of birds