parnassia vs grass-of-Parnassus

parnassia and grass-of-Parnassus both are nouns.

Word	Noun	Adjective	Verb	Adverb
parnassia	Yes	No	No	No
grass-of-Parnassus	Yes	No	No	No

As nouns, parnassia and grass-of-Parnassus are synonyms defined as:

parnassia and grass-of-Parnassus: any of various usually evergreen bog plants of the genus Parnassia having broad smooth basal leaves and a single pale flower resembling a buttercup

parnassia (noun)	grass-of-Parnassus (noun)
any of various usually evergreen bog plants of the genus Parnassia having broad smooth basal leaves and a single pale flower resembling a buttercup	any of various usually evergreen bog plants of the genus Parnassia having broad smooth basal leaves and a single pale flower resembling a buttercup