How do you differentiate "tu" and "vous"

Basically, TU and VOUS both mean "YOU". - "TU" when speaking or interacting with someone you know well, such as your friends, parents, siblings. --> Only when speaking to one of these people. (ex : hello dad ! how are you (TU)? ) "VOUS" can be used in two different situations. - Either when talking to an individual you do not know very well such as your headteacher, your doctor or a person you meet for the very first time. (ex. Hello Doctor, how are you (VOUS) ?) - You can also use "VOUS" when talking to several persons at a time. (ex. Hello friends, how are you (VOUS)?)