It's the same. There is no difference at all. Usually, "U" is seen as 3rd person. Which means: u heeft (because it's also hij/zij heeft) Or it can be seen as 2nd person. Which means: u hebt (because jij hebt) In spoken language, "u heeft" or "heeft u" is much more common and also what I usually say. When I write a formal letter, I use "u hebt" or "hebt u". In modern Dutch novels, "u heeft" is also more common. In short: both correct, "u heeft" is used more colloquially, "u hebt" is better for formal letters.