false oat vs tall oat grass

false oat and tall oat grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
false oat	Yes	No	No	No
tall oat grass	Yes	No	No	No

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

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

false oat (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