Cestrum diurnum vs shrub

Cestrum diurnum and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
Cestrum diurnum	Yes	No	No	No
shrub	Yes	No	No	No

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

Cestrum diurnum: West Indian evergreen shrub having clusters of funnel-shaped white flowers that are fragrant by day
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of Cestrum diurnum include bush.

Cestrum diurnum (noun)	shrub (noun)
West Indian evergreen shrub having clusters of funnel-shaped white flowers that are fragrant by day	a low woody perennial plant usually having several major stems