periwinkle vs subshrub

periwinkle and subshrub both are nouns.

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

As nouns, subshrub is a hypernym of periwinkle; that is, subshrub is a word with a broader meaning than periwinkle:

Other hypernyms of periwinkle include suffrutex.

periwinkle (noun)	subshrub (noun)
edible marine gastropod	low-growing woody shrub or perennial with woody base
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