"Usted" or "Ustedes (in plural)" are used in formal situations or with old people you don't know them. (Usted se llevó el mueble) "Tú" is for coloquial situations, is used with people that you knew them. (Tú te llevaste el mueble).

Tú is used for people your age and usted is more formal for elders or your peers to be respectful. Como estas tu? How are you? Como esta usted? How are you? But like i said its more formal and respectful

Fácil y rápido. Usted = Formal .- You should use this word for people who don't meet or when you are meeting a new person Tú= Informal.- You should use this word with friends and family