Holcus mollis vs creeping soft grass

Holcus mollis and creeping soft grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
Holcus mollis	Yes	No	No	No
creeping soft grass	Yes	No	No	No

As nouns, Holcus mollis and creeping soft grass are synonyms defined as:

Holcus mollis and creeping soft grass: European perennial grass with soft velvety foliage

Holcus mollis (noun)	creeping soft grass (noun)
European perennial grass with soft velvety foliage	European perennial grass with soft velvety foliage