title-holder vs rival

title-holder and rival both are nouns.

Word	Noun	Adjective	Verb	Adverb
title-holder	Yes	No	No	No
rival	Yes	Yes	Yes	No

As nouns, rival is a hypernym of title-holder; that is, rival is a word with a broader meaning than title-holder:

Other hypernyms of title-holder include challenger, competition, competitor, contender.

title-holder (noun)	rival (noun)
someone who has won first place in a competition	the contestant you hope to defeat

title-holder (adjective)	rival (adjective)
	as a rival in a competition

title-holder (verb)	rival (verb)
	be the rival of, be in competition with
	be equal to in quality or ability