Web services can only be invoked by HTTP (traditional webservice with
.asmx). While WCF Service or a WCF component can be invoked by any
protocol (like http, tcp etc.) and any transport type.
Second web services are not flexible. However, WCF Services are
flexible. If you make a new version of the service then you need to just
expose a new end. Therefore, services are agile and which is a very
practical approach looking at the current business trends.