bearwood vs buckthorn

bearwood and buckthorn both are nouns.

Word	Noun	Adjective	Verb	Adverb
bearwood	Yes	No	No	No
buckthorn	Yes	No	No	No

As nouns, buckthorn is a hypernym of bearwood; that is, buckthorn is a word with a broader meaning than bearwood:

bearwood: shrubby tree of the Pacific coast of the United States; yields cascara sagrada
buckthorn: a shrub or shrubby tree of the genus Rhamnus; fruits are source of yellow dyes or pigments

bearwood (noun)	buckthorn (noun)
shrubby tree of the Pacific coast of the United States; yields cascara sagrada	any shrub or small tree of the genus Bumelia
	a shrub or shrubby tree of the genus Rhamnus; fruits are source of yellow dyes or pigments
	an Old World plantain with long narrow ribbed leaves widely established in temperate regions