brown bent vs bent grass

brown bent and bent grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
brown bent	Yes	No	No	No
bent grass	Yes	No	No	No

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

brown bent: common grass with slender stems and narrow leaves
bent grass: grass for pastures and lawns especially bowling and putting greens

Other hypernyms of brown bent include bent-grass, bent.

brown bent (noun)	bent grass (noun)
common grass with slender stems and narrow leaves	grass for pastures and lawns especially bowling and putting greens