oleaster vs shrub

oleaster and shrub both are nouns.

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

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

oleaster: any of several shrubs of the genus Elaeagnus having silver-white twigs and yellow flowers followed by olivelike fruits
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of oleaster include bush.

oleaster (noun)	shrub (noun)
any of several shrubs of the genus Elaeagnus having silver-white twigs and yellow flowers followed by olivelike fruits	a low woody perennial plant usually having several major stems