While exposing apex class as SOAP web service, we declare the class as global and include a method with keyword Webservice and static. However in few scenarios I have seen few instance variable as are too declared with keyword WebService. What are the extra advantages to such variables?
According to the docs : You must use the webService keyword with any member variables that you want to expose as part of a Web service.
You can read more over here : https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_web_services_methods_considerations.htm