“Quand” and “lorsque” are similar, and sometimes they mean the same thing. “Quand” is more general, and it is mainly used for questions, for statements with time correlations or for contrasts. Questions: Quand dormez-vous? When do you sleep? Statements with time correlations: Je mange quand j’ai faim. I eat when I am hungry. Contrasts: Pourquoi pleurer quand on peut rire? Why cry when one can laugh? “Lorsque” is mainly used for statements with time correlations and for contrasts too. Statements with time correlations: Je bois lorsque j’ai soif. I drink when I am thirsty. Contrasts: Il est content lorsqu’elle l’ignore. He is happy when she ignores him. Please keep in mind that “quand” has many other uses, but the ones I mentioned are the most related to “lorsque”. I hope that helps.

Merci Beni