Attributes

WCF has [ServiceContract] attribute attached with the class.
WS has [WebService] attribute attached with the class.
WCF has [OperationContract] attribute attached with methods.
WS has[WebMethod] attribute attached with methods.

Hosting
WCF can be hosted on IIS, WAS, of self-hosting.
WS can be hosted on IIS.

XML
WCF uses using System.Runtime.Serialization; namespace for serialization.
WS uses using System.Xml.Serialization; namespace for serialization.

Transports
WCF support HTTP, TCP, MSMQ, P2P transport protocols.
WS support Http protocol.

Encoding
WCF supports XML, MTOM (Messaging Transmission Optimization Mechanism), Binary.
WS supports XML, MTOM, DIME (Direct Internet Message Encapsulation).