Override.cs

using System;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            A a = new A();
            A b = new B();

            a.Print();
            b.Print();

            Console.WriteLine(a.Prop);
            Console.WriteLine(b.Prop);

            A aa = new A();
            B bb = new B();

            aa.Print();
            bb.Print();

            Console.WriteLine(aa.Prop);
            Console.WriteLine(bb.Prop);

        }
    }

    class A
    {
        public virtual string Prop
        {
            get { return "Property of AAAA"; }
        }

        public virtual void Print()
        {
            Console.WriteLine("AAAA");
        }
    }

    class B : A
    {
        public override string Prop
        {
            get { return "Property of BBBB"; }
        }

        public override void Print()
        {
            Console.WriteLine("BBBB");
        }
    }
}