Difference of panchayat, dtcp, hntda

Dear all, I am planning to purchase a plot in housr road attibele, where the seller providing panchayat approval and A katha .. But not been registered with dtcp Nd hntda.. They r saying panchYat approval is suffient . 1: I just want to know panchayat approval is sufficient along with past previous years land Lord documents provided by seller ?? 2: I just want to know wht panchayat has power of authuriztion ? And wht dtcp has ? And wht hntda has??? . Kindly get back as earliest . Thanq u. Regards; Kalyan.