mercy vs pardon

mercy and pardon both are nouns.

Word	Noun	Adjective	Verb	Adverb
mercy	Yes	No	No	No
pardon	Yes	No	Yes	No

As nouns, pardon is a hyponym of mercy; that is, pardon is a word with a more specific, narrower meaning than mercy:

mercy: leniency and compassion shown toward offenders by a person or agency charged with administering justice
pardon: the formal act of liberating someone

Other hyponyms of mercy include commutation, re-sentencing, amnesty, free pardon, quarter, reprieve, respite.

mercy (noun)	pardon (noun)
leniency and compassion shown toward offenders by a person or agency charged with administering justice	the act of excusing a mistake or offense
alleviation of distress; showing great kindness toward the distressed	the formal act of liberating someone
a disposition to be kind and forgiving	a warrant granting release from punishment for an offense
the feeling that motivates compassion
something for which to be thankful

mercy (verb)	pardon (verb)
	grant a pardon to
	accept an excuse for