green bristlegrass vs bottle grass

green bristlegrass and bottle grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
green bristlegrass	Yes	No	No	No
bottle grass	Yes	No	No	No

As nouns, green bristlegrass and bottle grass are synonyms defined as:

green bristlegrass and bottle grass: European foxtail naturalized in North America; often a troublesome weed

Other synonyms of green bristlegrass include bottle-grass, green foxtail, rough bristlegrass, Setaria viridis.

green bristlegrass (noun)	bottle grass (noun)
European foxtail naturalized in North America; often a troublesome weed	European foxtail naturalized in North America; often a troublesome weed