alpine azalea vs shrub

alpine azalea and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
alpine azalea	Yes	No	No	No
shrub	Yes	No	No	No

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

alpine azalea: creeping mat-forming evergreen shrub of high mountain regions of Northern Hemisphere grown for its rose-pink flowers
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of alpine azalea include bush.

alpine azalea (noun)	shrub (noun)
creeping mat-forming evergreen shrub of high mountain regions of Northern Hemisphere grown for its rose-pink flowers	a low woody perennial plant usually having several major stems