grass family vs genus Arrhenatherum

grass family and genus Arrhenatherum both are nouns.

Word	Noun	Adjective	Verb	Adverb
grass family	Yes	No	No	No
genus Arrhenatherum	Yes	No	No	No

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