rosebush vs shrub

rosebush and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
rosebush	Yes	No	No	No
shrub	Yes	No	No	No

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

Other hypernyms of rosebush include bush.

rosebush (noun)	shrub (noun)
any of many shrubs of the genus Rosa that bear roses	a low woody perennial plant usually having several major stems