genus Campanula vs plant genus

genus Campanula and plant genus both are nouns.

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

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

genus Campanula (noun)	plant genus (noun)
large genus of herbs grown for their blossoms: bellflowers	a genus of plants