Both are different buddy..
For making client-server application we do use GUI.
GUI- you can have all kinds of objects like combobox, button, menu. etc
You can covert it to webbased application
you will have one or more server proc for each client proc.
The client procs will be deployed either in some webserver or on the workstation itself.
It looks like mainframe screen, Green screen.
It works same as mainframe screens.
Can not have GUI object on the screen like buttons and combobox.
Operations are function key based.
it will not have server proc inside. Instead it directly calls CABs.
it is deployed and generated in mainframes it self.