Agrostis nebulosa vs bent-grass

Agrostis nebulosa and bent-grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
Agrostis nebulosa	Yes	No	No	No
bent-grass	Yes	No	No	No

As nouns, bent-grass is a hypernym of Agrostis nebulosa; that is, bent-grass is a word with a broader meaning than Agrostis nebulosa:

Agrostis nebulosa: Spanish grass with light feathery panicles grown for dried bouquets
bent-grass: grass for pastures and lawns especially bowling and putting greens

Other hypernyms of Agrostis nebulosa include bent, bent grass.

Agrostis nebulosa (noun)	bent-grass (noun)
Spanish grass with light feathery panicles grown for dried bouquets	grass for pastures and lawns especially bowling and putting greens