genus Crassula vs plant genus

genus Crassula and plant genus both are nouns.

Word	Noun	Adjective	Verb	Adverb
genus Crassula	Yes	No	No	No
plant genus	Yes	No	No	No

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

genus Crassula: type genus of Crassulaceae; herbs and small shrubs having woody stems and succulent aerial parts
plant genus: a genus of plants

genus Crassula (noun)	plant genus (noun)
type genus of Crassulaceae; herbs and small shrubs having woody stems and succulent aerial parts	a genus of plants