kapuka vs shrub

kapuka and shrub both are nouns.

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

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

kapuka: small New Zealand broadleaf evergreen tree often cultivated in warm regions as an ornamental
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of kapuka include bush.

kapuka (noun)	shrub (noun)
small New Zealand broadleaf evergreen tree often cultivated in warm regions as an ornamental	a low woody perennial plant usually having several major stems