genus Didelphis vs mammal genus

genus Didelphis and mammal genus both are nouns.

Word	Noun	Adjective	Verb	Adverb
genus Didelphis	Yes	No	No	No
mammal genus	Yes	No	No	No

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

genus Didelphis (noun)	mammal genus (noun)
type genus of the family Didelphidae	a genus of mammals