meadow grass vs foxtail

meadow grass and foxtail both are nouns.

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

As nouns, foxtail is a hyponym of meadow grass; that is, foxtail is a word with a more specific, narrower meaning than meadow grass:

meadow grass: any of various grasses that thrive in the presence of abundant moisture
foxtail: grasses of the genera Alopecurus and Setaria having dense silky or bristly brushlike flowering spikes

Other hyponyms of meadow grass include foxtail grass, manna grass, sweet grass, Agrostis alba, Poa nemoralis, wood meadowgrass.

meadow grass (noun)	foxtail (noun)
any of various grasses that thrive in the presence of abundant moisture	grasses of the genera Alopecurus and Setaria having dense silky or bristly brushlike flowering spikes