Is there a difference between “throw” and “throw ex”?

Yes, there is a difference;

• throw ex resets the stack trace (so your errors would appear to originate from HandleException)

• throw doesn’t – the original offender would be preserved.

  static void Main(string[] args)
  {
      try
      {
          Method2();
      }
      catch (Exception ex)
      {
          Console.Write(ex.StackTrace.ToString());
          Console.ReadKey();
      }
  }
  
  private static void Method2()
  {
      try
      {
          Method1();
      }
      catch (Exception ex)
      {
          //throw ex resets the stack trace Coming from Method 1 and propogates it to the caller(Main)
          throw ex;
      }
  }
  
  private static void Method1()
  {
      try
      {
          throw new Exception("Inside Method1");
      }
      catch (Exception)
      {
          throw;
      }
  }