Hi,

    what is session?

       When ever u create session it will ask for map which it has to link.For each seesion we can have one map to link with session and worklet which is used as a resuable one can have number of sessions in it.

 What is Task

         Suppose u want to excecute some  Pre-Session or post session i..e...If u want to do some work after the exceution of session ,we can do it by task. Suppose ur creating two target  flat files in unix  from session(i..e mapping) then u want to concatenate this two target flat files then write concatenate shell script in unix and include the same in task. U can create reusable tasks which we can use it for every session when and they require....... thanks .......if u have any doubts regarding this mail me lingeshkumar.n@gmail.com