prizefighter vs gladiator

prizefighter and gladiator both are nouns.

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

As nouns, prizefighter and gladiator are synonyms defined as:

prizefighter (noun)	gladiator (noun)
a professional boxer	(ancient Rome) a professional combatant or a captive who entertained the public by engaging in mortal combat
	a professional boxer