mel just tell you that with what limitation you can release the aircraft.for eg if there is fault light in pax 1 then mel will tell that you can release aircraft if altitude maintained at less than 1000ft and with cargo doors empty,and your ddpg tell you what maintenance action require to release the aircraft.for eg:do bite test and shut off apu bleed for pax 1 and ddg tell you operation procedure for pilot,that what they need to do during mel for same.