What is the difference between postman and mail guard?

Both the posts are drawing same pay, same status but nature of duties are different. Postman is attached to delivery postoffice and his main duty is to deliver letters to public. His working hours will be day and time is fixed. No shifts. He will be given some area to deliver letters to the residents. This operation comes under postal division.

Mailguard is attached to sorting offices which comes under sorting division. His main duty is to check and collect the bags from sorting offices and deliver them to postoffices in the early hours and vice versa in the evenings. He has to sort the bags, load the bags also. He will have shift duty.