Formal Questions:
* Use "vous" to address the person. "Vous" is the formal "you".
* Use a more formal verb conjugation. For example, "pouvez-vous" instead of "peux-tu" (Can you...).
* Use more elaborate expressions. For instance, "Excusez-moi, pourriez-vous me dire..." (Excuse me, could you tell me...) instead of "Dis-moi..." (Tell me...).
* Often begin with a polite phrase like "Excusez-moi" (Excuse me), "Pardon" (Excuse me), or "S'il vous plaît" (Please).
Informal Questions:
* Use "tu" to address the person. "Tu" is the informal "you".
* Use a more familiar verb conjugation. For example, "peux-tu" instead of "pouvez-vous".
* Use simpler expressions. For instance, "Dis-moi..." (Tell me...) instead of "Excusez-moi, pourriez-vous me dire...".
Here are some examples:
Formal:
* Pouvez-vous me dire où est la gare, s'il vous plaît? (Can you tell me where the train station is, please?)
* Excusez-moi, auriez-vous l'heure, s'il vous plaît? (Excuse me, do you have the time, please?)
Informal:
* Tu peux me dire où est la gare? (Can you tell me where the train station is?)
* Tu as l'heure? (Do you have the time?)
When to use formal vs. informal:
* Formal: Use formal questions when addressing someone you don't know well, someone older than you, or someone in a position of authority.
* Informal: Use informal questions when addressing friends, family, or people you know well.
Note: In French, the choice of "vous" or "tu" is very important for conveying the right level of respect and familiarity. Using the wrong pronoun can be considered rude.