Poaceae vs genus Poa

Poaceae and genus Poa both are nouns.

Word	Noun	Adjective	Verb	Adverb
Poaceae	Yes	No	No	No
genus Poa	Yes	No	No	No

Poaceae (noun)	genus Poa (noun)
the grasses: chiefly herbaceous but some woody plants including cereals, bamboo, reeds, sugar cane	chiefly perennial grasses of cool temperate regions