What Silverlight is and how it differs from WPF?

Silverlight, formerly known as Windows Presentation Foundation Everywhere (WPF/E), is a cross-platform version of WPF. Basically, it is a subset of WPF that can run on a MAC or PC.

WPF can only run on MS Windows platform (XP or greater) with .NET 3.0 or later installed.

There are other differences, but most important is that WPF can make use of 3D objects, while Silverlight can do some faking 3D, but not true 3D. This is because WPF can make use of the host machine’s graphic cards, while Silverlight cannot.

The final difference is that Silverlight integrates right into an HTML page by using Silverlight browser plug-in, while WPF needs to be inserted into an IFRAME to mix with HTML content.

Silverlight is still being developed, and may be there are some changes in the future.