why less pay for guest teacher working under directorate of education delhi then teachers of MCD(municipal corporation of delhi)

WITH DUE RESPECT I WOULD LIKE TO DRAW YOUR KIND ATTENTION TOWARDS THE PROBLEM CONTINUOUSLY FACED BY THE GUEST TEACHERS (ASSISTANT TEACHERS) WHO ARE WORKING IN SKV(SARVODAYA KANYA VIDYALAYA)/SBV (SARVODAYA BAL VIDYALAYA) UNDER THE GOVERNMENT OF NCT OF DELHI BY DIRECTORATE OF EDUCATION. WE ARE WORKING ON PER DAY BASIS WHICH IS 380/- RS PER WORKING DAY WE HARDLY GET 7000 TO 8000 PER MONTH WHEREAS THE TEACHERS WORKING UNDER MCD(MUNICIPAL CORPORATION OF Delhi) IN MCD SCHOOLS WERE ALREADY GETTING 13500/- RS FIX MONTHLY SALARY AND FROM NOW THEY WILL BE PAID RS 21000 PER MONTH AS PER THE ANNOUNCEMENT MADE BY MCD ON SEPTEMBER 5. OUR QUESTION IS THAT WHEN : 1.THE QUALIFICATION 2.THE SELECTION PROCEDURE 3.THE WORK 4.THE WORKING TIME PER DAY IS SAME WHY THEY GET PAID MORE THEN US THE SALARY SHOULD BE SAME FOR ALL OF US. WE HAVE CLEARED CTET(CENTRAL TEACHER'S ELIGIBILITY TEST) ALSO BUT ONLY A FEW NUMBER OF MCD CONTRACT TEACHER'S HAVE QUALIFIED IT. IF THE WORK IS SAME THEN THE SALARY MUST BE SAME FOR BOTH MCD AS WELL AS GNCT TEACHERS WE ALL REQUEST YOU TO PLEASE LOOK FORWAD ON THIS PROBLEM WE WILL BE SO THANKFUL TO YOU