large periwinkle vs Vinca major

large periwinkle and Vinca major both are nouns.

Word	Noun	Adjective	Verb	Adverb
large periwinkle	Yes	No	No	No
Vinca major	Yes	No	No	No

As nouns, large periwinkle and Vinca major are synonyms defined as:

large periwinkle and Vinca major: plant having variegated foliage and used for window boxes

large periwinkle (noun)	Vinca major (noun)
plant having variegated foliage and used for window boxes	plant having variegated foliage and used for window boxes