California buckthorn vs Rhamnus californicus

California buckthorn and Rhamnus californicus both are nouns.

Word	Noun	Adjective	Verb	Adverb
California buckthorn	Yes	No	No	No
Rhamnus californicus	Yes	No	No	No

As nouns, California buckthorn and Rhamnus californicus are synonyms defined as:

California buckthorn and Rhamnus californicus: evergreen shrub of western United States bearing small red or black fruits

Other synonyms of California buckthorn include California coffee, coffeeberry.

California buckthorn (noun)	Rhamnus californicus (noun)
evergreen shrub of western United States bearing small red or black fruits	evergreen shrub of western United States bearing small red or black fruits