Abstract Base Class and Concrete Derived Class:             The base class that has one or more pure virtual functions is called the Abstract Base Class. These classes designed as a framework or layout for derived classes. An abstract base class cannot be instantiated, i.e. an object of its type cannot he defined. But, a pointer to an abstract base class can he defined.              ... 

Virtual Function:             A virtual function is a special type of member function. It is defined in the base class and may be redefined in any class derived from this base class. Its name in the base class and in the derived classes remains the same. Its definition in these classes may be different. The virtual function in derived class is executed through the pointer of the public base...