couch grass vs quack grass

couch grass and quack grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
couch grass	Yes	No	No	No
quack grass	Yes	No	No	No

As nouns, couch grass and quack grass are synonyms defined as:

couch grass and quack grass: European grass spreading rapidly by creeping rhizomes; naturalized in North America as a weed

Other synonyms of couch grass include Agropyron repens, dog grass, quackgrass, quick grass, witch grass, witchgrass.

couch grass (noun)	quack grass (noun)
European grass spreading rapidly by creeping rhizomes; naturalized in North America as a weed	European grass spreading rapidly by creeping rhizomes; naturalized in North America as a weed