yellow oleander vs shrub

yellow oleander and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
yellow oleander	Yes	No	No	No
shrub	Yes	No	No	No

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

yellow oleander: tropical American shrub or small tree having glossy dark green leaves and fragrant saffron yellow to orange or peach- colored flowers; all parts highly poisonous
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of yellow oleander include bush.

yellow oleander (noun)	shrub (noun)
tropical American shrub or small tree having glossy dark green leaves and fragrant saffron yellow to orange or peach- colored flowers; all parts highly poisonous	a low woody perennial plant usually having several major stems