grass family vs genus Cenchrus

grass family and genus Cenchrus both are nouns.

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

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