Parallel vs PLINQ

gistfile1.cs

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Net;
using System.Threading.Tasks;

namespace AsyncTest
{
    class Program
    {
        static void Main(string[] args)
        {
            RunPLinq();
            //RunParallel();
        }

        static void RunPLinq()
        {
            Stopwatch span = Stopwatch.StartNew();

            GetUrls()
                .Select(async url => await Download(url))
                .Select(i => i.Result)
                .Select(img => new
                {
                    mainImg = ResizeImage(img, 600, 600),
                    smallImg = ResizeImage(img, 300, 300)
                })
                .AsParallel()
                .ToList();
            Console.WriteLine("WTF :" + span.Elapsed);

            Console.ReadLine();
        }

        static void RunParallel()
        {
            Stopwatch span = Stopwatch.StartNew();
            var exceptions = new ConcurrentQueue<Exception>();

            // Execute the complete loop and capture all exceptions.
            Parallel.ForEach(GetUrls(), async url =>
            {
                try
                {
                    var image = await Download(url);
                    var mainImg = ResizeImage(image, 600, 600);
                    var smallImg = ResizeImage(image, 300, 300);
                    Console.WriteLine("WTF :" + url);
                    Console.WriteLine("WTF :" + span.Elapsed);
                }
                // Store the exception and continue with the loop.                    
                catch (Exception e) { exceptions.Enqueue(e); }
            });

            // Throw the exceptions here after the loop completes.
            if (exceptions.Count > 0) throw new AggregateException(exceptions);

            Console.WriteLine("WTF :" + span.Elapsed);
            Console.ReadLine();
        }

        public static Bitmap ResizeImage(Image image, int width, int height)
        {
            var destRect = new Rectangle(0, 0, width, height);
            var destImage = new Bitmap(width, height);

            destImage.SetResolution(image.HorizontalResolution, image.VerticalResolution);

            using (var graphics = Graphics.FromImage(destImage))
            {
                graphics.CompositingMode = CompositingMode.SourceCopy;
                graphics.CompositingQuality = CompositingQuality.HighQuality;
                graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
                graphics.SmoothingMode = SmoothingMode.HighQuality;
                graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;

                using (var wrapMode = new ImageAttributes())
                {
                    wrapMode.SetWrapMode(WrapMode.TileFlipXY);
                    graphics.DrawImage(image, destRect, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel, wrapMode);
                }
            }

            return destImage;
        }

        private static IEnumerable<string> GetUrls()
        {
            var urls = new string[]
            {
                "https://assets.miumiu.com/content/images/products/details/5BH609_2EJA_F068Z_V_DJM-1.jpg",
                "https://assets.miumiu.com/content/images/products/details/5BH609_2EJA_F068Z_V_DJM-2.jpg",
                "https://assets.miumiu.com/content/images/products/details/5BH609_2EJA_F068Z_V_DJM-3.jpg",
                "https://assets.miumiu.com/content/images/products/details/5BH609_2EJA_F068Z_V_DJM-4.jpg"
            };

            foreach (string item in urls)
            {
                Console.WriteLine("Who Am I?");
                yield return item;
            }
        }

        private static async Task<Bitmap> Download(string url)
        {
            WebClient client = new WebClient();
            var bytes = await client.DownloadDataTaskAsync(url);
            Console.WriteLine(url);
            return new Bitmap(new MemoryStream(bytes));
        }
    }
}