mountain fetterbush vs shrub

mountain fetterbush and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
mountain fetterbush	Yes	No	No	No
shrub	Yes	No	No	No

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

mountain fetterbush: ornamental evergreen shrub of southeastern United States having small white bell-shaped flowers
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of mountain fetterbush include bush.

mountain fetterbush (noun)	shrub (noun)
ornamental evergreen shrub of southeastern United States having small white bell-shaped flowers	a low woody perennial plant usually having several major stems