penance vs punishment

penance and punishment both are nouns.

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

As nouns, punishment is a hypernym of penance; that is, punishment is a word with a broader meaning than penance:

Other hypernyms of penance include penalisation, penalization, penalty.

penance (noun)	punishment (noun)
voluntary self-punishment in order to atone for some wrongdoing	the act of punishing, or the infliction of a penalty
a Catholic sacrament; repentance and confession and atonement and absolution
remorse for your past conduct