beach heather vs subshrub

beach heather and subshrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
beach heather	Yes	No	No	No
subshrub	Yes	No	No	No

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

beach heather: small heathlike plant covered with white down growing on beaches in northeastern North America
subshrub: low-growing woody shrub or perennial with woody base

Other hypernyms of beach heather include suffrutex.

beach heather (noun)	subshrub (noun)
small heathlike plant covered with white down growing on beaches in northeastern North America	low-growing woody shrub or perennial with woody base