genus Aquila vs bird genus

genus Aquila and bird genus both are nouns.

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

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

genus Aquila (noun)	bird genus (noun)
a genus of Accipitridae, containing the true eagles (Aquila)	a genus of birds