genus Apteryx vs bird genus

genus Apteryx and bird genus both are nouns.

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

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

genus Apteryx (noun)	bird genus (noun)
type genus of the Apterygidae: kiwis	a genus of birds