penalty vs penance

penalty and penance both are nouns.

Word	Noun	Adjective	Verb	Adverb
penalty	Yes	No	No	No
penance	Yes	No	No	No

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

penalty (noun)	penance (noun)
the act of punishing, or the infliction of a penalty	voluntary self-punishment in order to atone for some wrongdoing
the disadvantage or painful consequences of an action or condition	a Catholic sacrament; repentance and confession and atonement and absolution
(games) a handicap or disadvantage that is imposed on a competitor (or a team) for an infraction of the rules of the game	remorse for your past conduct
a payment required for not fulfilling a contract