Duvida em C#

            SortedList lista = new SortedList();
            
            foreach (string s in Directory.GetFiles("C:\\"))
            {
                FileInfo finfo = new FileInfo(s);
                lista.Add(finfo.Name, "Arquivo");
            }
            foreach (string s in Directory.GetDirectories("C:\\"))
            {
                DirectoryInfo dinfo = new DirectoryInfo(s);
                lista.Add(dinfo.Name, "Diretório");
            }
            foreach (string s in lista.Keys)
            {
                Console.WriteLine(s + " - " + lista[s].ToString());
            }
            Console.Read();

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            List<string> directoryCollection = new List<string>(new string[1] { @"C:\" });

            for (int index = 0; index < directoryCollection.Count; index++)
            {
                string dir = directoryCollection[index];

                Console.WriteLine("############################################");

                StringBuilder oStringBuilder = new StringBuilder();

                oStringBuilder.Append("Pasta - ");
                oStringBuilder.Append(dir);

                Console.WriteLine(oStringBuilder.ToString());

                try
                {
                    directoryCollection.AddRange(Directory.GetDirectories(dir));

                    new List<string>(Directory.GetFiles(dir)).ForEach(item =>
                    {
                        oStringBuilder = new StringBuilder();

                        oStringBuilder.Append("Arquivo - ");
                        oStringBuilder.Append(new FileInfo(item).Name);

                        Console.WriteLine(oStringBuilder.ToString());
                    });
                }
                catch (Exception oException)
                {
                    Console.WriteLine(oException.Message);
                }

                Console.WriteLine("############################################");
                Console.WriteLine("");
            }

            Console.Read();
        }
    }
}