self-mortification vs penance

self-mortification and penance both are nouns.

Word	Noun	Adjective	Verb	Adverb
self-mortification	Yes	No	No	No
penance	Yes	No	No	No

As nouns, self-mortification and penance are synonyms defined as:

self-mortification and penance: voluntary self-punishment in order to atone for some wrongdoing

Other synonyms of self-mortification include self-abasement.

self-mortification (noun)	penance (noun)
voluntary self-punishment in order to atone for some wrongdoing	voluntary self-punishment in order to atone for some wrongdoing
	a Catholic sacrament; repentance and confession and atonement and absolution
	remorse for your past conduct