kindness vs mercy

kindness and mercy both are nouns.

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

As nouns, mercy is a hypernym of kindness; that is, mercy is a word with a broader meaning than kindness:

Other hypernyms of kindness include mercifulness.

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