grass family vs Bromus

grass family and Bromus both are nouns.

Word	Noun	Adjective	Verb	Adverb
grass family	Yes	No	No	No
Bromus	Yes	No	No	No

grass family (noun)	Bromus (noun)
the grasses: chiefly herbaceous but some woody plants including cereals, bamboo, reeds, sugar cane	a genus of grasses of the family Gramineae