Difference between accessing a class method via -> and via :: ?

What's the Difference between accessing a class method via -> and via ::?
The -> is used for accessing properties and methods of instantiated objects.
:: is used for accesing static methods or attributes and don't require to instantiate an object of the class.

Example:
<?php
class Person
{
  var $name = Raj; 


  public function getName()
  {
    return $this->name;
  }


  public static function getAge()
  {
    return "25";
  }
}
$person = new $person(); 
echo $person->getName();//Require to instantiate an object of the class.
echo person::getAge();//:: is used for accesing static methods(getAge), so don't require to instantiate an object of the  class