unmatched vs unrivaled

unmatched and unrivaled both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unmatched	No	Yes	No	No
unrivaled	No	Yes	No	No

As adjectives, unmatched and unrivaled are synonyms defined as:

Other synonyms of unmatched include matchless, nonpareil, one, one and only, peerless, unmatchable, unrivalled.

unmatched (adjective)	unrivaled (adjective)
eminent beyond or above comparison	eminent beyond or above comparison
of the remaining member of a pair