Understanding the difference between throw ex and throw, why is the original StackTrace preserved in this example:

    static void Main(string[] args)
    {
        try
        {
            LongFaultyMethod();
        }
        catch (System.Exception ex)
        {
            Console.WriteLine(ex.StackTrace);
        }
    }

    static void LongFaultyMethod()
    {
        try
        {
            int x = 20;
            SomethingThatThrowsException(x);
        }
        catch (Exception)
        {
            throw;
        }
    }

    static void SomethingThatThrowsException(int x)
    {
        int y = x / (x - x);
    }

But not in this one:

    static void Main(string[] args)
    {
        try
        {
            LongFaultyMethod();
        }
        catch (System.Exception ex)
        {
            Console.WriteLine(ex.StackTrace);
        }
    }

    static void LongFaultyMethod()
    {
        try
        {
            int x = 20;
            int y = x / (x - 20);
        }
        catch (Exception)
        {
            throw;
        }
    }

The second scenario is producing the same output as throw ex would?

In both cases, one expects to see the line number where y is initialized.