feather reed grass vs Calamagrostis acutiflora

feather reed grass and Calamagrostis acutiflora both are nouns.

Word	Noun	Adjective	Verb	Adverb
feather reed grass	Yes	No	No	No
Calamagrostis acutiflora	Yes	No	No	No

As nouns, feather reed grass and Calamagrostis acutiflora are synonyms defined as:

feather reed grass and Calamagrostis acutiflora: a variety of reed grass

Other synonyms of feather reed grass include feathertop.

feather reed grass (noun)	Calamagrostis acutiflora (noun)
a variety of reed grass	a variety of reed grass