csharp how does comparing datetime work

                
                        using System;
public class Demo {
   public static void Main(){
      DateTime d1 = new DateTime(2019, 12, 20, 6, 20, 40);
      DateTime d2 = new DateTime(2019, 11, 20, 6, 20, 40);
      Console.WriteLine("DateTime 1 = {0:dd} {0:y}, {0:hh}:{0:mm}:{0:ss} ", d1);
      Console.WriteLine("DateTime 2 = {0:dd} {0:y}, {0:hh}:{0:mm}:{0:ss} ", d2);
      int res = DateTime.Compare(d1, d2);
      // returns equal to 0 since d1 is equal to d2
      Console.WriteLine(res);
   }
}