Difference between Polymorphism and Method Overloading

The difference between polymorphism and method overloading is in the time when the actual method to execute is determined. The reason for this is that when a method is overloaded, such as in:
account = new BankAccount();
account = new BankAccount(1000);

The compiler can tell which constructor to use by the method signature, including the number and types of parameters provided. This selection of a method to use at compile time, before the program ever runs is called early binding.
On the other hand, when we use a polymorphic method call such as x.getMeasure() the actual getMeasure() method called depends on what type of object x refers to. Because objects are not constructed until the program runs, the method called is determined at run-time. Therefore, the virtual machine, not the compiler selects the appropriate method. This method selection is called late-binding.

Links:
Polymorphism
Interfaces and Polymorphism