Christmas rose vs Helleborus niger

Christmas rose and Helleborus niger both are nouns.

Word	Noun	Adjective	Verb	Adverb
Christmas rose	Yes	No	No	No
Helleborus niger	Yes	No	No	No

As nouns, Christmas rose and Helleborus niger are synonyms defined as:

Christmas rose and Helleborus niger: European evergreen plant with white or purplish rose-like winter-blooming flowers

Other synonyms of Christmas rose include black hellebore, winter rose.

Christmas rose (noun)	Helleborus niger (noun)
European evergreen plant with white or purplish rose-like winter-blooming flowers	European evergreen plant with white or purplish rose-like winter-blooming flowers