Lithospermum vs plant genus

Lithospermum and plant genus both are nouns.

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

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

Lithospermum: annual or perennial herbaceous or shrubby plants; cosmopolitan except Australia
plant genus: a genus of plants

Lithospermum (noun)	plant genus (noun)
annual or perennial herbaceous or shrubby plants; cosmopolitan except Australia	a genus of plants