boxwood vs shrub

boxwood and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
boxwood	Yes	No	No	No
shrub	Yes	No	No	No

As nouns, shrub is a hypernym of boxwood; that is, shrub is a word with a broader meaning than boxwood:

Other hypernyms of boxwood include bush.

boxwood (noun)	shrub (noun)
evergreen shrubs or small trees	a low woody perennial plant usually having several major stems
very hard tough close-grained light yellow wood of the box (particularly the common box); used in delicate woodwork: musical instruments and inlays and engraving blocks