mercy vs forgiveness

mercy and forgiveness both are nouns.

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

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

mercy (noun)	forgiveness (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	compassionate feelings that support a willingness to forgive
a disposition to be kind and forgiving
the feeling that motivates compassion
something for which to be thankful