Demonstrates how `throw ex` replaces the stack trace in an exception, while `throw` preserves it.

ThrowVsThrowEx.cs

using System;

class Program
{
    static void One() { Two(); }
    static void Two() { Three(); }
    static void Three() { throw new Exception("Error"); }

    static void Main(string[] args)
    {
        Console.WriteLine("RE-THROWING AN EXCEPTION WITH `throw ex`");
        CatchExceptionAndPrintToConsole(() =>
        {
            try { One(); }
            catch (Exception ex) { throw ex; }
        });

        Console.WriteLine("\n\nRE-THROWING AN EXCEPTION WITH `throw`");
        CatchExceptionAndPrintToConsole(() =>
        {
            try { One(); }
            catch (Exception) { throw; }
        });

        Console.WriteLine("\n\nPress any key to exit");
        Console.ReadKey();
    }

    static void CatchExceptionAndPrintToConsole(Action action)
    {
        try { action(); }
        catch (Exception ex) { Console.WriteLine(ex.ToString()); }
    }
}