penance vs punishment

penance

noun
  • A voluntary self-imposed punishment for a sinful act or wrongdoing. It may be intended to serve as reparation for the act. 

  • Any instrument of self-punishment. 

  • A sacrament in some Christian churches. 

verb
  • To impose penance; to punish. 

punishment

noun
  • A penalty to punish wrongdoing, especially for crime. 

  • Any harsh treatment or experience; rough handling. 

  • The act or process of punishing, imposing and/or applying a sanction. 

  • A suffering by pain or loss imposed as retribution 

How often have the words penance and punishment occurred in a corpus of books? (source: Google Ngram Viewer )