genus Steatornis vs bird genus

genus Steatornis and bird genus both are nouns.

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

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

genus Steatornis (noun)	bird genus (noun)
type and sole genus of the family Steatornithidae	a genus of birds