heavyweight vs prizefighter

heavyweight and prizefighter both are nouns.

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

As nouns, prizefighter is a hypernym of heavyweight; that is, prizefighter is a word with a broader meaning than heavyweight:

Other hypernyms of heavyweight include gladiator.

heavyweight (noun)	prizefighter (noun)
A weight class division in combat sports, often the heaviest.	a professional boxer
a person of exceptional importance and reputation
a professional boxer who weighs more than 190 pounds
a wrestler who weighs more than 214 pounds
a very large person; impressive in size or qualities
an amateur boxer who weighs no more than 201 pounds