What is the difference between RIA and WCF services?

Answer:

Some points are as under

1) WCF is concerned with technical aspects of communication between servers across tiers and message data management whereas RIA Web Services delegates this
functionality to WCF.

2) WCF is a generic service that could be used in Windows Forms for example whereas RIA Web Services is focused on Silverlight and ASP.NET clients

3) WCF does not generate source code to address class business logic such as validation that may need to be shared across tiers like RIA Web Services does.

4) The RIA Services can either exist on top of WCF or replace the WCF layer with RIA Services using alternatice data source e.g. an ORM layer(EF/NHibernate etc.)

5) RIA Services allow serializing LINQ queries between the client and server.