mercy vs kindness

mercy and kindness both are nouns.

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

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

Other hyponyms of mercy include compassion, pity, forgivingness, lenience, leniency, lenity, mildness.

mercy (noun)	kindness (noun)
leniency and compassion shown toward offenders by a person or agency charged with administering justice	a kind act
alleviation of distress; showing great kindness toward the distressed	the quality of being warmhearted and considerate and humane and sympathetic
a disposition to be kind and forgiving	tendency to be kind and forgiving
the feeling that motivates compassion
something for which to be thankful