Cyperaceae vs Cyperus

Cyperaceae and Cyperus both are nouns.

Word	Noun	Adjective	Verb	Adverb
Cyperaceae	Yes	No	No	No
Cyperus	Yes	No	No	No

As nouns, Cyperus is a hyponym of Cyperaceae; that is, Cyperus is a word with a more specific, narrower meaning than Cyperaceae:

Cyperaceae: bulrush, chufa, cotton grass, papyrus, umbrella plant
Cyperus: type genus of Cyperaceae; grasslike rhizomatous herbs; cosmopolitan except very cold regions

Other hyponyms of Cyperaceae include genus Cyperus.

Cyperaceae (noun)	Cyperus (noun)
bulrush, chufa, cotton grass, papyrus, umbrella plant	type genus of Cyperaceae; grasslike rhizomatous herbs; cosmopolitan except very cold regions