What is the difference between S'il te plait and S'il vous plait?

Answer 1

S'il te plait (please) is informal and singular. That means you are addressing a single person you are familiar with.

S'il vous plait (please) is formal or plural. You may be adressing several persons at once, or a single one with whom the realtionship is more distant (your boss, a stranger, ...)

To your son, mother, girlfriend: "s'il te plait, passe moi le sel" (pass me the salt, please) - s'il vous plait, venez (please, come [you all])

To several of your kids (plural): taisez-vous un peu, s'il vous plait (please, be quiet a moment) - s'il vous plait, venez (please, come [you all])

To your boss: Je voudrais vous parler de mon augmentation, s'il vous plait (I'd like to talk to you about my salary raise, please) - s'il vous plait, venez (please, come)