buster vs bronco buster

buster and bronco buster both are nouns.

Word	Noun	Adjective	Verb	Adverb
buster	Yes	No	No	No
bronco buster	Yes	No	No	No

As nouns, buster and bronco buster are synonyms defined as:

Other synonyms of buster include broncobuster.

buster (noun)	bronco buster (noun)
a person (or thing) that breaks up or overpowers something	a person who breaks horses
a person who breaks horses
a robust child
an informal form of address for a man
a person born in the generation following the baby boom when the birth rate fell dramatically