herb roberts vs Geranium robertianum

herb roberts and Geranium robertianum both are nouns.

Word	Noun	Adjective	Verb	Adverb
herb roberts	Yes	No	No	No
Geranium robertianum	Yes	No	No	No

As nouns, herb roberts and Geranium robertianum are synonyms defined as:

herb roberts and Geranium robertianum: a sticky low herb with small reddish-purple flowers; widespread in the Northern Hemisphere

Other synonyms of herb roberts include herb robert, herbs robert.

herb roberts (noun)	Geranium robertianum (noun)
a sticky low herb with small reddish-purple flowers; widespread in the Northern Hemisphere	a sticky low herb with small reddish-purple flowers; widespread in the Northern Hemisphere