I realize that it seems to be a duplicate of What is the difference between a Field and a Property in C#? but my question has a slight difference (from my point of view):
Once I know that
Is there any difference (except the style/future development ones), like some type of control in setting the property?
Is there any additional difference between:
public string MyString { get; set; }
and
public string myString;
(I am aware that, that the first version requires C# 3.0 or above and that the compiler does create the private fields.)
Encapsulation.
In the second instance you've just defined a variable, in the first, there is a getter / setter around the variable. So if you decide you want to validate the variable at a later date - it will be a lot easier.
Plus they show up differently in Intellisense :)
Edit: Update for OPs updated question - if you want to ignore the other suggestions here, the other reason is that it's simply not good OO design. And if you don't have a very good reason for doing it, always choose a property over a public variable / field.