"Du" and "Ni"
Swedish people what´s the difference between two words mening "you". "Du" and "ni"?
True. Ni may be used as Vous or fancy addressing, though it's not common today.
They mean the same thing. The difference is the proper use of "ni" compared to "vous". Only use "ni" when adressing more than one person. This is of course different from "vous" which can be used to adress both one and more than one person.
You actually could use "vous" and "ni" the same way. It would be perfectly correct Swedish, but perhaps not perfectly correct manners.