difference between polymorphism and overloading

[GCDEF]

Overloading is polymorphism: ad-hoc polymorphism; what you stated is supertype/subtype polymorphism.

class Cbase
{
    void Func();
    void Func(int); //Overloading
    virtual void PolyFunc();
};

class CDerived : public CBase
{
    void PolyFunc();
};

Func is overloaded. PolyFunc is, or can be, polymorphic. It's not really the same concept. Overloading gives a different signature to a function so you can call the function with diffferent argument types and numbers. In simplistic terms, polymorphism means that the function will be called for the correct class when accessed through a base class pointer.