bearded darnel vs ryegrass

bearded darnel and ryegrass both are nouns.

Word	Noun	Adjective	Verb	Adverb
bearded darnel	Yes	No	No	No
ryegrass	Yes	No	No	No

As nouns, ryegrass is a hypernym of bearded darnel; that is, ryegrass is a word with a broader meaning than bearded darnel:

bearded darnel: weedy annual grass often occurs in grainfields and other cultivated land; seeds sometimes considered poisonous
ryegrass: any of several annual or perennial Eurasian grasses

Other hypernyms of bearded darnel include rye grass.

bearded darnel (noun)	ryegrass (noun)
weedy annual grass often occurs in grainfields and other cultivated land; seeds sometimes considered poisonous	any of several annual or perennial Eurasian grasses