foxtail vs foxtail grass

foxtail and foxtail grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
foxtail	Yes	No	No	No
foxtail grass	Yes	No	No	No

As nouns, foxtail and foxtail grass are synonyms defined as:

foxtail and foxtail grass: grasses of the genera Alopecurus and Setaria having dense silky or bristly brushlike flowering spikes

foxtail (noun)	foxtail grass (noun)
grasses of the genera Alopecurus and Setaria having dense silky or bristly brushlike flowering spikes	grasses of the genera Alopecurus and Setaria having dense silky or bristly brushlike flowering spikes
	ground pine thickly covered with bristly leaves; widely distributed in barren sandy or peaty moist coastal regions of eastern and southeastern United States