carob bean vs carob bean tree

carob bean and carob bean tree both are nouns.

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

carob bean (noun)	carob bean 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