bush-league vs bush

bush-league is not a noun while bush is a noun.

Word	Noun	Adjective	Verb	Adverb
bush-league	No	Yes	No	No
bush	Yes	Yes	Yes	No

As adjectives, bush-league and bush are synonyms defined as:

bush-league (noun)	bush (noun)
	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

bush-league (adjective)	bush (adjective)
not of the highest quality or sophistication	not of the highest quality or sophistication

bush-league (verb)	bush (verb)
	provide with a bushing