This inside functions in javascript

Question

this.x = 9;
var module = {
  x: 81,
  getX: function() { return this.x; }
};

module.getX(); // 81

var getX = module.getX;
console.log(getX())  // 9

In the first situation i understand that x = 81, because it point to the outer scope where x = 81, but
why getX at the end is 9?