multiflora rose vs rosebush

multiflora rose and rosebush both are nouns.

Word	Noun	Adjective	Verb	Adverb
multiflora rose	Yes	No	No	No
rosebush	Yes	No	No	No

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

multiflora rose: vigorously growing rose having clusters of numerous small flowers; used for hedges and as grafting stock
rosebush: any of many shrubs of the genus Rosa that bear roses

Other hypernyms of multiflora rose include rose.

multiflora rose (noun)	rosebush (noun)
vigorously growing rose having clusters of numerous small flowers; used for hedges and as grafting stock	any of many shrubs of the genus Rosa that bear roses