Hello Valentin !

First, sorry for my english, I am currently trying to improve with Italki.


About the word "Quand" : we, french speakers, use this word when we want to ask a question about time (not "lorsque") instead of "when" at the beginning of the question.

For example : When did you go to the cinema last time ? Quand es-tu allé au cinéma la dernière fois ?

                            When will he go at the supermarket ? Quand ira-t-il au supermarché ?


However, we can also find the word "lorsque" (and also "quand" as synonyms) in a question, but only if it isn't to ask a question about time.
For example : When you were at cinema yesterday, which film did you see ? Quand tu étais au cinéma hier, quel film as-tu vu ?

                            When you'll go at the supermarket, could you buy tomatoes please ? Quand tu iras au supermarché, peux-tu acheter des tomates s'il te plait ?

In those examples, you can use "lorsque" or "quand".


But it's difficult to explain the difference between those words, because  they are used as synonyms.


About me , I use "Quand" when I speak et I want to use a familiar language, and I use "Lorsque" when I write and I want to use a more formal language.


I hope this first answer will help you, and that others comments will complete this one.


Bye Valentin.

Thank you very much for your help Amelie

Merci!