unmatched vs one and only

unmatched and one and only both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unmatched	No	Yes	No	No
one and only	No	Yes	No	No

As adjectives, unmatched and one and only are synonyms defined as:

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

unmatched (adjective)	one and only (adjective)
eminent beyond or above comparison	eminent beyond or above comparison
of the remaining member of a pair