boxer vs prizefighter

boxer and prizefighter both are nouns.

Word	Noun	Adjective	Verb	Adverb
boxer	Yes	No	No	No
prizefighter	Yes	No	No	No

As nouns, prizefighter is a hyponym of boxer; that is, prizefighter is a word with a more specific, narrower meaning than boxer:

boxer (noun)	prizefighter (noun)
a breed of stocky medium-sized short-haired dog with a brindled coat and square-jawed muzzle developed in Germany	a professional boxer
someone who fights with his fists for sport
a workman employed to pack things into containers