quack grass vs dog grass

quack grass and dog grass both are nouns.

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

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

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

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

quack grass (noun)	dog 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