Arrhenatherum vs family Gramineae

Arrhenatherum and family Gramineae both are nouns.

Word	Noun	Adjective	Verb	Adverb
Arrhenatherum	Yes	No	No	No
family Gramineae	Yes	No	No	No

Arrhenatherum (noun)	family Gramineae (noun)
oat grass	the grasses: chiefly herbaceous but some woody plants including cereals, bamboo, reeds, sugar cane