bush league vs minor league

bush league and minor league both are nouns.

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

As nouns, bush league and minor league are synonyms defined as:

bush league and minor league: a league of teams that do not belong to a major league (especially baseball)

Other synonyms of bush league include minors.

bush league (noun)	minor league (noun)
a league of teams that do not belong to a major league (especially baseball)	a league of teams that do not belong to a major league (especially baseball)