red periwinkle vs periwinkle

red periwinkle and periwinkle both are nouns.

Word	Noun	Adjective	Verb	Adverb
red periwinkle	Yes	No	No	No
periwinkle	Yes	No	No	No

As nouns, red periwinkle and periwinkle are synonyms defined as:

red periwinkle and periwinkle: commonly cultivated Old World woody herb having large pinkish to red flowers

red periwinkle (noun)	periwinkle (noun)
commonly cultivated Old World woody herb having large pinkish to red flowers	edible marine gastropod
	small edible marine snail; steamed in wine or baked
	chiefly trailing poisonous plants with blue flowers
	commonly cultivated Old World woody herb having large pinkish to red flowers