1. All Web services are APIs but all APIs are not Web services.
2. Web services might not perform all the operations that an API
would perform.
3. A Web service uses only three styles of use: SOAP, REST and
XML-RPC for communication whereas API may use any style for
communication.
4. A Web service always needs a network for its operation whereas
an API doesn’t need a network for its operation.
5. An API facilitates interfacing directly with an application whereas
a Web service is a required a path.