Upload is function used to write data from a file in the 
presentation server to internal table.here you get a dialog-
box to enter the path of the file name.

Ws_upload also perfoms the same function , but without 
screen. here you do not get a dialog-box, rather you need 
to type the path of the file name.

in case of upload user dialogue is required i.e.path is 
mandatory b4 execution of prog..
in case of ws-upload no user dialogue is req i.e.we can 
mention da path b4 or at the time of execution..