What's the difference between "return View()" and "return PartialView()"

Return View() - Renders an .aspx|.cshtml page

• Renders a normal .aspx page that can also contain Partial Views

Return PartialView() - Renders .ascx|.cshtml Control

• Renders a segment of HTML to the browser that can be requested through AJAX or Non-AJAX requests alike.

View() returns ViewResult PartialView() returns PartialViewResult both inherit from ViewResultBase

The difference is described by Reflector below...

public class PartialViewResult : ViewResultBase
{
   // Methods
   protected override ViewEngineResult FindView(ControllerContext context)
   {
      ViewEngineResult result = base.ViewEngineCollection.FindPartialView(context, base.ViewName);
      if (result.View != null)
      {
         return result;
      }
      StringBuilder builder = new StringBuilder();
      foreach (string str in result.SearchedLocations)
      {
         builder.AppendLine();
         builder.Append(str);
      }
      throw new InvalidOperationException(string.Format(CultureInfo.CurrentUICulture, MvcResources.Common_PartialViewNotFound, new object[] { base.ViewName, builder }));
   }
}


public class ViewResult : ViewResultBase
{
   // Fields
   private string _masterName;

   // Methods
   protected override ViewEngineResult FindView(ControllerContext context)
   {
      ViewEngineResult result = base.ViewEngineCollection.FindView(context, base.ViewName, this.MasterName);
      if (result.View != null)
      {
         return result;
      }
      StringBuilder builder = new StringBuilder();
      foreach (string str in result.SearchedLocations)
      {
         builder.AppendLine();
         builder.Append(str);
      }
      throw new InvalidOperationException(string.Format(CultureInfo.CurrentUICulture, MvcResources.Common_ViewNotFound, new object[] { base.ViewName, builder }));
   }

   // Properties
   public string MasterName
   {
      get
      {
         return (this._masterName ?? string.Empty);
      }
      set
      {
         this._masterName = value;
      }
   }
}

return PartialView() returns HTML code fragment and it is used with ViewUserControls - ASCX files. The main advantage of using "return PartialView()" is when you don't want to render all the other HTML page stuff, like HTML, BODY, HEAD tags.

One of the most common uses by me is when I want to render just the user control based on whether the request to an action is AJAX call.

So I have a View called MyControl.aspx where I use RenderPartial HTML helper and I have a partial View named MyControl.ascx where I do the actual render.

I can switch between those two in my controller action like this:

if (Request.IsAjaxRequest())
    return PartialView("MyControl"); // this renders MyControl.ascx

return View(); // this render MyControl.aspx

A controller action typically returns a PartialView when AJAX is used, and an update of the page region represented by the partial view is performed. The normal way to use partial views is simply to call Html.RenderPartial inside your main view.