wsimport:

• The wsimport tool reads a WSDL and generates all the required artifacts for web service development, deployment, and invocation.
• It supports the top-down approach to developing JAX-WS Web services, where you are starting from a wsdl.
• wsimport tool generated JAX-WS portable artifacts include Service Endpoint Interface (SEI), Service, Exception class mapped from wsdl:fault (if any), JAXB generated value types (mapped java classes from schema types) etc. These artifacts can be packaged in a WAR file with the WSDL and schema documents along with the endpoint implementation to be deployed.

Ex Command :

wsimport http://localhost:8090/MyJaxWSService?wsdl

wsgen:
The wsgen tool reads an existing web service implementation class and generates the required JAX–WS portable artifacts for web service development and deployment. The wsgen tool can be used for bottoms-up approach, where you are starting from a service endpoint implementation rather than a wsdl.

Ex Command :

wsgen -verbose -keep -cp . in.malliktalksjava.service.HellowWorldService

• wsgen and wsimport generate request and response wrapper bean classes and the JAXB classes. However, wsgen generates the JAXB classes and put them in a jaxws folder and wsimport does not put those classes in any folder instead they will be placed in the current directory.
• JAX-WS artifacts generated can be used by both service implementation and client implementation.
• Using wsgen you can also generate the wsdl based on webservice implementation class.