American spicebush vs shrub

American spicebush and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
American spicebush	Yes	No	No	No
shrub	Yes	No	No	No

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

American spicebush: deciduous shrub of the eastern United States having highly aromatic leaves and bark and yellow flowers followed by scarlet or yellow berries
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of American spicebush include bush.

American spicebush (noun)	shrub (noun)
deciduous shrub of the eastern United States having highly aromatic leaves and bark and yellow flowers followed by scarlet or yellow berries	a low woody perennial plant usually having several major stems