furze vs shrub

furze and shrub both are nouns.

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

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

furze: very spiny and dense evergreen shrub with fragrant golden-yellow flowers; common throughout western Europe
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of furze include bush.

furze (noun)	shrub (noun)
very spiny and dense evergreen shrub with fragrant golden-yellow flowers; common throughout western Europe	a low woody perennial plant usually having several major stems