marsh rosemary vs subshrub

marsh rosemary and subshrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
marsh rosemary	Yes	No	No	No
subshrub	Yes	No	No	No

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

marsh rosemary: any of various plants of the genus Limonium of temperate salt marshes having spikes of white or mauve flowers
subshrub: low-growing woody shrub or perennial with woody base

Other hypernyms of marsh rosemary include suffrutex.

marsh rosemary (noun)	subshrub (noun)
any of various plants of the genus Limonium of temperate salt marshes having spikes of white or mauve flowers	low-growing woody shrub or perennial with woody base