sand sage vs sage brush

sand sage and sage brush both are nouns.

Word	Noun	Adjective	Verb	Adverb
sand sage	Yes	No	No	No
sage brush	Yes	No	No	No

As nouns, sage brush is a hypernym of sand sage; that is, sage brush is a word with a broader meaning than sand sage:

sand sage: silver-haired shrub of central and southern United States and Mexico; a troublesome weed on rangelands
sage brush: any of several North American composite subshrubs of the genera Artemis or Seriphidium

Other hypernyms of sand sage include sagebrush.

sand sage (noun)	sage brush (noun)
silver-haired shrub of central and southern United States and Mexico; a troublesome weed on rangelands	any of several North American composite subshrubs of the genera Artemis or Seriphidium