HtmlString vs. MvcHtmlString

Question

HtmlString vs. MvcHtmlString

What are the differences bettween those two, or when to prefer one over the other?

Edit:

Answer 1

HtmlString was only introduced in .Net 4.0.

In ASP.Net 3.5 MVC 2.0, you should use MvcHtmlString.
In .Net 4.0, you should use HtmlString. (which is simpler)