In Visual Studio 2010, when you try to add a WCF Service, you will see the following 2 kinds of WCF services:
There are “WCF Data Service” and "WCF Service", so what are their differents ?
WCF Data Service formerly called ADO.NET Data Services, it focused on providing new client and server side features for data service developers including improved Data Binding, Projections, Server Driven Paging, Count and Enhanced Blob support as well as many other improvements.
More information please read Microsoft WCF Data Service Official site.
Also, a good example is Building an AtomPub Server Using WCF Data Services
WCF Service is just our regular Windows Communication Foundation which is a part of the .NET Framework that provides a unified programming model for rapidly building service-oriented applications that communicate across the web and the enterprise.
The official site is here