It is possible to 'override' a method with the same name and parameters and provide a different implementation in a derived class, if the base class declares the method as overridable. (override in C#)

It is also possible to use the 'new' keyword in C# to provide a different implementation of a method which may be or may not be declared as overridable by the base class.

The derived class also may use the same method name as in the base class and provide different parameter list and different implementation which will 'overload' the base class method. Here it is not necessary that the method be declared as overridable in the base class.