Formal:
* Vous êtes: This is the formal "you" and is used for someone you don't know well, someone older than you, or someone you are showing respect to.
Informal:
* Tu es: This is the informal "you" and is used for friends, family, children, or anyone you are close to.
Example Sentences:
* Vous êtes un bon ami. (You are a good friend.) - Formal
* Tu es très intelligente. (You are very intelligent.) - Informal
Let me know if you would like to see other examples!