quack grass vs witchgrass

quack grass and witchgrass both are nouns.

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

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

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

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

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