In any case, remorse and regret remain two anguished feelings, after all they refer to something that one would have desired but was not. With one substantial difference, those who live in remorse have at least tried to forge their own destiny and to live life in all its aspects. On the other hand, those who live in regret presumably have let fate decide for them.
Remorse is disturbance dictated by a mistake made in the past. Disturbed by something that has been done that has brought about unhappiness or pain. There could be remorse for example a poorly done job, a wrong maneuver at the wheel, a decision made in a hurry, with little reasoning.
The downside is regret, that is, what has been lost, things, events or people do not matter.
The downside is regret, that is, what has been lost, things, events or people do not matter. Moments that have not been understood (think of the famous Carpe diem), and that have gotten out of hand. Or a person removed from their life, journeys that have never begun, objects that have never been purchased.
They are like two currents of thought, in which perhaps remorse is better, since at least you have tried, you have acted and you have not remained motionless. But the past, read nostalgia, can be anything and everything. It may be twenty years ago or a second ago, so everything becomes useless while looking for a correct answer to the original question.