From one role to another, no - would help if you could provide a use case.
But from one user to another yes, you can re-assign tasks from the Task UI if you have privs to do so.
You can also use task assignment algorithms to automate the assignment of tasks to users.
Actually now I trying for a small application of vacation tracker, like
If an employee raises an request , it will go to manager's worklist, if he wants to approve he can approve or he can delegate the task to employee's supervisor. Here manager and supervisor are in different role. How to delegate the task between them. This is my exact requirement.
Then you told about task assignment algorithms, can you please provide more information on this? like how to do it and is there any documents related to that?
Thanks in Advance,