The difference between French "tu" and "vous".
There are two ways to say you in French language when you address French people: "tu" and "vous". There is no problem if you address several people - it’s always "vous". But what should you use if you address a single person?
French "Vous" is a formal, polite form. It demonstrates your respect to the person. Generally, you have to use it with:
French "Tu" is familiar and informal.
Advice:If you are not sure how to address your interlocutor use the more polite form of French "you" – "vous". If the person you address prefers more informal relationship he can tell you: "Tu peux (or vous pouvez) me tutoyer", that means "You can use "tu" when speaking to me".
If you feel that using "tu" is OK, you may ask: "Est-ce qu'on peut se tutoyer?" (Can we address each other as "tu"?) to be sure that your interlocutor doesn’t mind.