WSDL 1.2 was renamed WSDL 2.0 because of its substantial differences from WSDL 1.1. Some of these changes include:
.Adding further semantics to the description language. This is one of the reasons for making targetNamespace a required attribute of the definitions element in WSDL 2.0.
.Removal of message constructs. These are specified using the XML schema type system in the types element.
.No support for operator overloading.
.PortTypes renamed to interfaces. Support for interface inheritance is achieved by using the extends attribute in the interface element.
.Ports renamed to endpoints.