sweet pepperbush vs shrub

sweet pepperbush and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
sweet pepperbush	Yes	No	No	No
shrub	Yes	No	No	No

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

sweet pepperbush: shrub of eastern and southern coastal United States having beautiful racemes of spice-scented white flowers
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of sweet pepperbush include bush.

sweet pepperbush (noun)	shrub (noun)
shrub of eastern and southern coastal United States having beautiful racemes of spice-scented white flowers	a low woody perennial plant usually having several major stems