There's very little difference. "Regret" means just he felt sorry about it. "Lament" means that he felt sorry about it, and said so. "Regret" is a feeling. "Lament" is an expression of feeling. Since intense feelings of regret usually lead to lamentation, "to lament" can also be used just to mean "to regret strongly." "A lament" suggests a strong outward show of grief: crying, and wailing. However, it is often used to mean a kind of complaint: a wistful, sad complaint, rather than an angry complaint.

The best way I can think to explain the differences is when a person laments, they express sadness, emotional pain, and regret about events that have happened. A person can lament over the loss of a loved one, or they can lament a sports team losing a game. To lament is to mourn.

However, regret is less external; regret is more of being disappointed over an outcome and wishing it didn't happen this way. In america, people usually relate regret to events in our control, so we could wish we did not quit a job, wish we did not sing a song too loud, wish we drove faster, or wish we could change our past actions for a different outcome; all of those examples are examples of regret.

The key is that regret is not showing or expressing sad emotions for what has happened, that is lementing. Regret is more to do with wishing our actions in the past were different, and has no relation to the expression of those feelings.

I hope this helps! ¡Ciao!

I think the meaning is the same. But the nuance of "lament" is more dramatic and stylistic. Regret is 後悔する。Lament is 悼む or 嘆く. There is a book of poems in the Bible called "Lamentations" so perhaps when people see the word "Lament" they think of it as a classical, ancient sadness. I hope that makes sense.

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