return new RedirectResult() vs return Redirect()

straight from the source

// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.using System.Diagnostics.CodeAnalysis;using System.Web.Mvc.Properties;namespace System.Web.Mvc{    // represents a result that performs a redirection given some URI    public class RedirectResult : ActionResult    {        [SuppressMessage("Microsoft.Design", "CA1054:UriParametersShouldNotBeStrings", MessageId = "0#", Justification = "Response.Redirect() takes its URI as a string parameter.")]        public RedirectResult(string url)            : this(url, permanent: false)        {        }        [SuppressMessage("Microsoft.Design", "CA1054:UriParametersShouldNotBeStrings", MessageId = "0#", Justification = "Response.Redirect() takes its URI as a string parameter.")]        public RedirectResult(string url, bool permanent)        {            if (String.IsNullOrEmpty(url))            {                throw new ArgumentException(MvcResources.Common_NullOrEmpty, "url");            }            Permanent = permanent;            Url = url;        }        public bool Permanent { get; private set; }        [SuppressMessage("Microsoft.Design", "CA1056:UriPropertiesShouldNotBeStrings", Justification = "Response.Redirect() takes its URI as a string parameter.")]        public string Url { get; private set; }        public override void ExecuteResult(ControllerContext context)        {            if (context == null)            {                throw new ArgumentNullException("context");            }            if (context.IsChildAction)            {                throw new InvalidOperationException(MvcResources.RedirectAction_CannotRedirectInChildAction);            }            string destinationUrl = UrlHelper.GenerateContentUrl(Url, context.HttpContext);            context.Controller.TempData.Keep();            if (Permanent)            {                context.HttpContext.Response.RedirectPermanent(destinationUrl, endResponse: false);            }            else            {                context.HttpContext.Response.Redirect(destinationUrl, endResponse: false);            }        }    }}

The second argument determines whether the response is a 302 (temporary) or 301 permanent redirection. By default, the value is false.

The second method is on Controller and is simply a convenience method. This method has been around for a number of versions of MVC (as far back as at least 2), but IIRC, the addition of the Permanent part to RedirectResult I think has come in in MVC 4 (I don't recall seeing it in MVC 3).

// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.using System.Diagnostics.CodeAnalysis;using System.Globalization;using System.IO;using System.Security.Principal;using System.Text;using System.Web.Mvc.Async;using System.Web.Mvc.Properties;using System.Web.Profile;using System.Web.Routing;namespace System.Web.Mvc{    [SuppressMessage("Microsoft.Maintainability", "CA1506:AvoidExcessiveClassCoupling", Justification = "Class complexity dictated by public surface area")]    public abstract class Controller : ControllerBase, IActionFilter, IAuthorizationFilter, IDisposable, IExceptionFilter, IResultFilter, IAsyncController, IAsyncManagerContainer    {      // omitted for brevity      [SuppressMessage("Microsoft.Design", "CA1054:UriParametersShouldNotBeStrings", MessageId = "0#", Justification = "Response.Redirect() takes its URI as a string parameter.")]      protected internal virtual RedirectResult Redirect(string url)      {          if (String.IsNullOrEmpty(url))          {              throw new ArgumentException(MvcResources.Common_NullOrEmpty, "url");          }          return new RedirectResult(url);      }    }}

this.Redirect(string url) - It will internally create new object of RedirectResult class and do temporary redirection.

new RedirectResult(string url, bool permanent) - It will redirect but gives you an option to redirect permanently or temporary.

They do the same thing. The Redirect method of the controller creates a new RedirectResult. If you instantiate the RedirectResult you also have the ability to add a parameter which determines whether the redirect is permanent (or not).