Initialising variables in a constructor or in the class body

Newbie & Debugging Questions
#1

Hi guys,

This has been bothering me recently as I create more and more classes for my game. Is there a real world difference between these 2 fictional classes:

class PlaceHolder {

  int x;

  public PlaceHolder() {
    this.x = 5;
  }
}

class PlaceHolder {

  int x = 5;

  public PlaceHolder() {
    //  nothing doing here
  }
}

As far as I can tell they do the same thing. Am I right in this observation or is there a reason to do one over the other?

I notice in my code that I vary between the 2 styles and sometimes in the same class!