wool grass vs plume grass

wool grass and plume grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
wool grass	Yes	No	No	No
plume grass	Yes	No	No	No

As nouns, plume grass is a hypernym of wool grass; that is, plume grass is a word with a broader meaning than wool grass:

wool grass: grass often cultivated for its long white-ribbed leaves and large plumes resembling those of pampas grass
plume grass: a reedlike grass of the genus Erianthus having large plumes

wool grass (noun)	plume grass (noun)
grass often cultivated for its long white-ribbed leaves and large plumes resembling those of pampas grass	a reedlike grass of the genus Erianthus having large plumes
sedge of eastern North America having numerous clustered woolly spikelets