blue curls vs subshrub

blue curls and subshrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
blue curls	Yes	No	No	No
subshrub	Yes	No	No	No

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

blue curls: any of several plants of the genus Trichostema having whorls of small blue flowers
subshrub: low-growing woody shrub or perennial with woody base

Other hypernyms of blue curls include suffrutex.

blue curls (noun)	subshrub (noun)
any of several plants of the genus Trichostema having whorls of small blue flowers	low-growing woody shrub or perennial with woody base