staff tree vs bush

staff tree and bush both are nouns.

Word	Noun	Adjective	Verb	Adverb
staff tree	Yes	No	No	No
bush	Yes	Yes	Yes	No

As nouns, bush is a hypernym of staff tree; that is, bush is a word with a broader meaning than staff tree:

Other hypernyms of staff tree include shrub.

staff tree (noun)	bush (noun)
any small tree or twining shrub of the genus Celastrus	hair growing in the pubic area
	dense vegetation consisting of stunted trees or bushes
	a large wilderness area
	a low woody perennial plant usually having several major stems

staff tree (adjective)	bush (adjective)
	not of the highest quality or sophistication

staff tree (verb)	bush (verb)
	provide with a bushing