Who Is An Off Role Employee?

What is the difference between a off role and on role employee? How can I recognise who is an on role employee?

Dear Rishabh
The correct wsord is "ROLL" and not "ROLE" !!!
Roll implies the Roll or Register of the Employees working in a Company.
Any employee whose name appears in the "Rolls of the Company" is an ON-ROLL employee;
those who are working under a Contractor, are OFF-Roll employees.
Hope the issue is clear now..