California sage vs sage brush

California sage and sage brush both are nouns.

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

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

California sage: low ashy-grey California shrub
sage brush: any of several North American composite subshrubs of the genera Artemis or Seriphidium

Other hypernyms of California sage include sagebrush.

California sage (noun)	sage brush (noun)
low ashy-grey California shrub	any of several North American composite subshrubs of the genera Artemis or Seriphidium