WCF is an extension - it's a web service, but you can expose it over TCP/IP, or named pipes, in addition to just using HTTP.
Also, WCF has lots more options for security and so on.
Data Representation :
Major Difference is That Web Services Use XmlSerializer But WCF Uses
DataContractSerializer which is better in Performance as Compared to XmlSerializer.
Important difference between DataContractSerializer and XMLSerializer.
* A practical benefit of the design of the DataContractSerializer is better performance over Xmlserializer.
* XML Serialization does not indicate the which fields or properties of the type are serialized into XML where as DataCotratSerializer Explicitly shows the which fields or properties are serialized into XML.
* The DataContractSerializer can translate the HashTable into XML.
Service Development
Web Service use the WebMethod to specifiy the method.
The ServiceContractAttribute specifies that the interface defines a WCF service contract, and the OperationContractAttribute indicates which, if any, of the methods of the interface define operations of the service contract.
Hosting
You can also host a WCF service inside your own app - you don't have to use IIS for hosting the web service (ASMX).
Binding :
Multiple Binding Allwoed.you can define Multiple End point.
Exception Handling
In ASP.NET Web services, unhandled exceptions are returned to clients as SOAP faults.
In WCF services, unhandled exceptions are not returned to clients as SOAP faults to prevent sensitive information being inadvertently exposed through the exceptions. A configuration setting is provided to have unhandled exceptions returned to clients for the purpose of debugging.
Multiple End point :
This had the benefit of being able to write a service once, and allowing many different kinds of clients to consume the same service (i.e. Java clients can use HTTP, .NET clients can use TCP, legacy can use MSMQ, etc.).
In conclusion: WCF IS web services - just much more flexible and much more useful than straight ASMX web services.
More information :
http://www.codeproject.com/KB/WCF/WCFMultipleHosting.aspx
WCF is not same as remoting.Remoting works only on Microsoft plateform.
WCF is a unification technology which unites the following technologies:-
.NET remoting
MSMQ
Web services
COM+.
Binding Comaprison
http://mkdot.net/blogs/dejan/archive/2008/03/31/wcf-binding-decision.aspx
