genus Cairina vs bird genus

genus Cairina and bird genus both are nouns.

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

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

genus Cairina (noun)	bird genus (noun)
a genus of Anatidae containing two species of duck (Cairina)	a genus of birds