CompareList

   public class Product : IComparableItem<Product>
   {
       public string Name { get; set; }
       public decimal Cost { get; set; }

       public string GetKeysToFindAddedItems()
       {
           return Name;
       }

       public string GetKeysToFindDeletedItems()
       {
           return Name;
       }

       public string GetKeysToFindUpdatedItems()
       {
           return string.Format("{0}{1}",Name,Cost);
       }
   }
      
  
   //Then within main method

  class Program
   {
       static void Main(string[] args)
       {
           List<Product> newProductList = new List<Product> { new Product { Name = "TV", Cost = 400 }, new Product { Name = "USB", Cost=12 } };
           List<Product> oldProductList = new List<Product> { new Product { Name = "TV", Cost = 450 } , new Product { Name = "MP3 Player", Cost = 20 } };

           var comparer = new ListComparer<Product>(newProductList, oldProductList);
           var added = comparer.GetAddedItems();
           var deleted = comparer.GetDeletedItems();
           var updated = comparer.GetUpdatedItems();

           System.Console.WriteLine("Added product {0}",added.FirstOrDefault().Name);
           System.Console.WriteLine("Updated product {0}", updated.FirstOrDefault().Name);
           System.Console.WriteLine("Deleted product {0}", deleted.FirstOrDefault().Name);
       }
   }