genus Leptoptilus vs bird genus

genus Leptoptilus and bird genus both are nouns.

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

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

genus Leptoptilus (noun)	bird genus (noun)
adjutant birds and marabous	a genus of birds