override is for polymorphic behavior of the member function/method. new is for member hiding / member shadowing.

new keyword - New Definition for a method.

overide keyword - Override existing definition for a method.

using System;

using System.Data;

using System.Diagnostics;

class Base

public virtual void Message()

sealed class Derived : Base

public override/new void Message()

class Test

static void Main()

Base obj = new Derived() as Base;