philadelphus vs shrub

philadelphus and shrub both are nouns.

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

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

philadelphus: any of various chiefly deciduous ornamental shrubs of the genus Philadelphus having white sweet-scented flowers, single or in clusters; widely grown in temperate regions
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of philadelphus include bush.

philadelphus (noun)	shrub (noun)
any of various chiefly deciduous ornamental shrubs of the genus Philadelphus having white sweet-scented flowers, single or in clusters; widely grown in temperate regions	a low woody perennial plant usually having several major stems