Remorso vs. arrependimento
While both remorso and arrependimento relate to feeling bad about a past action, they are not interchangeable. The key difference lies in the nature and consequence of the feeling: remorso is a passive, tormenting guilt, while arrependimento is an active regret that often implies a desire for change.
Remorso
B2Remorso is a deep, painful, and often corrosive feeling of guilt over a wrongdoing. It's a passive state of self-torment where the focus is on the negative feeling itself, not necessarily on changing or making amends. It is the heavy weight of a bad conscience.
Ele sentia um remorso terrível por ter mentido para os pais.
(He felt a terrible remorse for having lied to his parents.)
O remorso não o deixava dormir à noite, mas ele era orgulhoso demais para pedir desculpas.
(The remorse wouldn't let him sleep at night, but he was too proud to apologize.)
Ela vive atormentada pelo remorso de não ter ajudado quando pôde.
(She lives tormented by the remorse of not having helped when she could.)
Ele cometeu o crime e agora sofre de remorso, mas isso não muda o que ele fez.
(He committed the crime and now suffers from remorse, but that doesn't change what he did.)
Arrependimento
B1Arrependimento is the recognition of a mistake, accompanied by a feeling of regret and a wish to have done things differently. It is more active and constructive than remorso, as it often includes a desire to change one's behavior or to repair the damage done. It can range from simple regret to deep repentance.
Meu maior arrependimento foi não ter viajado mais quando era jovem.
(My biggest regret was not traveling more when I was young.)
Cheio de arrependimento, ele voltou para pedir perdão e prometeu mudar.
(Full of repentance, he came back to ask for forgiveness and promised to change.)
Sinto arrependimento por ter sido rude com você ontem.
(I regret being rude to you yesterday.)
O arrependimento sincero dele o levou a confessar tudo à polícia.
(His sincere repentance led him to confess everything to the police.)
Summary
In essence, remorso is the pain you feel after doing wrong, a self-focused torment. Arrependimento is the realization that you did wrong, coupled with a desire to undo the action or change your future behavior. You can feel remorso without arrependimento (feeling guilty but not wanting to change), but sincere arrependimento often contains an element of remorso (feeling guilty because you recognize your mistake).