witchgrass vs quack grass

witchgrass and quack grass both are nouns.

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

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

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

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

witchgrass (noun)	quack grass (noun)
North American grass with slender brushy panicles; often a weed on cultivated land	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