Uri mapping and uri routing

I'm reading a book on Silverlight 4. It uses terms "uri mapping" and "uri routing", but I can't see any difference. They seem to me as the same thing. Please somebody explain the difference.

btw. When I want to use "nice" url's, I use UriMapper class and define some mappings, so I expect this is "uri mapping". So where is any special "uri routing" class and how it differs from UriMapper?

citation: "In addition to Uri Mapping, the navigation framework in Silverlight supports Uri Routing. For example if yo开发者_如何学运维u placed all of your navigation views in a subdirectory named Views, you can follow a naming convention that you set. Then setup Uri Routes such as the following:

<nav:UriMapping Uri="{}{p}" MappedUri="/Views/{p}.xaml" />

"

[Note that this is my very first question on this forum. I hope it's all right.]

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UriMapper is a concept in the Silverlight Navigation Framework (System.Windows.Controls.Navigation.dll, in the Silverlight SDK). "URI routing" is typically referring to the feature in ASP.NET, but it depends on how that author is using it - they may simply be using two terms to refer to the same feature.

If you can show some example sentences from the book that are confusing you, that may help.