couch grass vs Agropyron repens

couch grass and Agropyron repens both are nouns.

Word	Noun	Adjective	Verb	Adverb
couch grass	Yes	No	No	No
Agropyron repens	Yes	No	No	No

As nouns, couch grass and Agropyron repens are synonyms defined as:

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

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

couch grass (noun)	Agropyron repens (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