The major difference between the SharePoint CSOM 2010 and the SharePoint 2013 is the introduction of the REST API. In SharePoint, the client.svc is the WCF Service which gives you the functionality of the client side access of the SharePoint objects through the JavaScript or the SilverLight or the .Net library. Whereas in SharePoint 2010 the client.svc is not accessed directly from the REST.API whilst the SharePoint 2013 supports a direct access of the REST API. Thus, any device can access SharePoint 2013 using a Client side object model.