Agrostis vs plant genus

Agrostis and plant genus both are nouns.

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

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

Agrostis: annual or perennial grasses cosmopolitan in Northern Hemisphere: bent grass (so named from `bent' meaning an area of unfenced grassland)
plant genus: a genus of plants

Agrostis (noun)	plant genus (noun)
annual or perennial grasses cosmopolitan in Northern Hemisphere: bent grass (so named from `bent' meaning an area of unfenced grassland)	a genus of plants