What is the difference (if any) between Html.Partial(view, model) and Html.RenderPartial(view,model) in MVC2?

Question

Other than the type it returns and the fact that you call it differently of course

<% Html.RenderPartial(...); %>
<%= Html.Partial(...) %>  

If they are different, why would you call one rather than the other one?
The definitions:

// Type: System.Web.Mvc.Html.RenderPartialExtensions
// Assembly: System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35
// Assembly location: C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET MVC 2\Assemblies\System.Web.Mvc.dll

using System.Web.Mvc;

namespace System.Web.Mvc.Html
{
    public static class RenderPartialExtensions
    {
        public static void RenderPartial(this HtmlHelper htmlHelper, string partialViewName);
        public static void RenderPartial(this HtmlHelper htmlHelper, string partialViewName, ViewDataDictionary viewData);
        public static void RenderPartial(this HtmlHelper htmlHelper, string partialViewName, object model);

        public static void RenderPartial(this HtmlHelper htmlHelper, string partialViewName, object model,
                                     ViewDataDictionary viewData);
    }
}

// Type: System.Web.Mvc.Html.PartialExtensions
// Assembly: System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35
// Assembly location: C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET MVC 2\Assemblies\System.Web.Mvc.dll

using System.Web.Mvc;

namespace System.Web.Mvc.Html
{
    public static class PartialExtensions
    {
        public static MvcHtmlString Partial(this HtmlHelper htmlHelper, string partialViewName);

        public static MvcHtmlString Partial(this HtmlHelper htmlHelper, string partialViewName,
                                        ViewDataDictionary viewData);

        public static MvcHtmlString Partial(this HtmlHelper htmlHelper, string partialViewName, object model);

        public static MvcHtmlString Partial(this HtmlHelper htmlHelper, string partialViewName, object model,
                                        ViewDataDictionary viewData);
    }
}

Answer 1

The only difference is that Partial returns an MvcHtmlString, and must be called inside <%= %>, whereas RenderPartial returnsvoid and renders directly to the view.

If you look at the source code, you'll see that they both call the same internal method, passing a StringWriter for it to render to.

You would call Partial if you want to view, save, or manipulate the generated HTML instead of writing it to the page.

Answer 2

HTML.RenderPartial is not returning HTML markup like most other helper methods. In place of, the method writes content directly to the response stream, which is why developer must call it like a entire line of C#, using a semicolon. This is slightly more effectual than buffering the rendered HTML from the partial view, since it will be written to the response stream anyway.