When should I go for Silverlight and when XNA?

Question

I don't have much knowledge about Windows Phone 7 development. I know there exist two paths for an app development. Silverlight or XNA. Before I start I would like to know for what scenarios Silverlight is the best choice and for what kind of apps it makes more sense to use XNA?

Answer 1

Silverlight is designed around building applications. As such, it includes a retained graphics model (re-drawing is handled for you) and wide range of user interface elements including both interactive controls and controls that perform layout logic.

XNA is designed around building games. As such, it includes an immediate graphics model (you must draw every frame) and game-friendly features like a content pipeline for importing graphics and low level audio support.

There is nothing stopping you using Silverlight for games and XNA for applications, but unless you have a good reason for switching it around you'll find yourself fighting against the framework while trying to do simple things.

Neil Knight mentioned you can use mix them in Mango, though the mix involves using XNA in a Silverlight application and not the other way around.