Griselinia littoralis vs shrub

Griselinia littoralis and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
Griselinia littoralis	Yes	No	No	No
shrub	Yes	No	No	No

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

Griselinia littoralis: 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 Griselinia littoralis include bush.

Griselinia littoralis (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