locust bean vs carob tree

locust bean and carob tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
locust bean	Yes	No	No	No
carob tree	Yes	No	No	No

locust bean (noun)	carob tree (noun)
long pod containing small beans and sweetish edible pulp; used as animal feed and source of a chocolate substitute	evergreen Mediterranean tree with edible pods; the biblical carob