fire thorn vs shrub

fire thorn and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
fire thorn	Yes	No	No	No
shrub	Yes	No	No	No

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

fire thorn: any of various thorny shrubs of the genus Pyracantha bearing small white flowers followed by hard red or orange-red berries
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of fire thorn include bush.

fire thorn (noun)	shrub (noun)
any of various thorny shrubs of the genus Pyracantha bearing small white flowers followed by hard red or orange-red berries	a low woody perennial plant usually having several major stems