Ursus vs mammal genus

Ursus and mammal genus both are nouns.

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

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

Ursus: type genus of Ursidae: brown bears; in some classifications genus Ursus includes all bears
mammal genus: a genus of mammals

Ursus (noun)	mammal genus (noun)
type genus of Ursidae: brown bears; in some classifications genus Ursus includes all bears	a genus of mammals