Brunfelsia americana vs shrub

Brunfelsia americana and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
Brunfelsia americana	Yes	No	No	No
shrub	Yes	No	No	No

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

Brunfelsia americana: West Indian shrub with fragrant showy yellowish-white flowers
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of Brunfelsia americana include bush.

Brunfelsia americana (noun)	shrub (noun)
West Indian shrub with fragrant showy yellowish-white flowers	a low woody perennial plant usually having several major stems