wool grass vs genus Scirpus

wool grass and genus Scirpus both are nouns.

Word	Noun	Adjective	Verb	Adverb
wool grass	Yes	No	No	No
genus Scirpus	Yes	No	No	No

wool grass (noun)	genus Scirpus (noun)
grass often cultivated for its long white-ribbed leaves and large plumes resembling those of pampas grass	rhizomatous perennial grasslike herbs
sedge of eastern North America having numerous clustered woolly spikelets