French rye vs tall oat grass

French rye and tall oat grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
French rye	Yes	No	No	No
tall oat grass	Yes	No	No	No

As nouns, French rye and tall oat grass are synonyms defined as:

French rye and tall oat grass: coarse perennial Eurasian grass resembling oat; found on roadside verges and rough grassland and in hay meadows; introduced in North America for forage

Other synonyms of French rye include Arrhenatherum elatius, evergreen grass, false oat, tall meadow grass.

French rye (noun)	tall oat grass (noun)
coarse perennial Eurasian grass resembling oat; found on roadside verges and rough grassland and in hay meadows; introduced in North America for forage	coarse perennial Eurasian grass resembling oat; found on roadside verges and rough grassland and in hay meadows; introduced in North America for forage