wpf VS Silverlight

WPF:
Ships as part of the .NET Framework (version 3.0 and onward)
Runs as Windows application or as web "browser application" (called XBAP, for "XAML Browser Application"). Note that XBAPs run only in Internet Explorer with .NET 3.0 and in both Internet Explorer and Firefox with .NET 3.5.
Runs on Windows machines only (Windows XP, Windows Server 2003, Windows Vista, and Windows Server 2008)
Richest functionality, including 3D graphics
Silverlight:
Ships independently
Runs in web browsers only (Internet Explorer, Firefox, Safari)
Runs on Windows or Mac operating systems (also on Linux via Moonlight, which is an open source implementation of Silverlight based on Mono)
Functionality is a subset of WPF's feature set
WPF is a more mature technology and was designed with a richer feature set. It also has the advantage of being able to run in a browser or as an installed Windows-Form-type app.
Silverlight has a broader reach. You can access Silverlight from many operating systems and web browsers.
The most important reason to choose one over the other should be based on the intended audience for the application. For example, if a corporation is designing an application for internal use only and every employee has Windows XP as the company standard OS, then go with WPF to leverage the richer feature set. If a corporation is designing an external-facing website, then Silverlight is the better choice because potential customers can access


WPF advantages over Silverlight
v Full access to all the Windows API and the full .NET API
o E.g. TCP/Binary WCF support
v Powerful printing support
v Desktop or browser hosted with Customizable Sandbox
o XBAP works on IE and Firefox
v Offline support
v Easy integration with other UI technologies
o WPF controls can be hosted in Office, WPF app can call Office API
o WPF controls can be hosted in WinForm
o WPF apps can host WinForm and ActiveX controls
v Proven technology (3.0, 3.5, 3.5 SP1)
v Virtualization (data or visuals) for large data (from 3.5 sp1)
v Large third party controls selection
v Hardware accelerated, 3D

Silverlight advantages over WPF
 Small runtime install 4 MB, 1 min, no reboot
o Default auto updating (no admin rights needed in Vista for runtime updates)
o Can be easily deployed even on login script or GPO
 No app deployment
o App is cached in browser cache
 Cross Platform, Cross Browser
o Windows 2000, XP, Vista, 2003, 2008, Mac OS
o Linux through partnership with Novell
 Easier to learn
o Due to the reduced API subset
 Can be integrated in current web pages and web based portals
o Is an island on the page
o Full access to the Browser DOM
o Fully scriptable from JavaScript
 Share code and components between Intra and Internet solutions
 In future it will run on Mobiles, CE