carob tree vs locust bean

carob tree and locust bean both are nouns.

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

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