What is the difference between model number 5 and M and F and N in iPhone?

M – Brand new device, meaning the device was purchased new. F – Refurbished device, meaning the device has been through refurbishing process. N – Replacement device, meaning the originally bought device was replaced by this model likely due to a service request.

But the model number is 5 or 5L Refurbished by an Apple Authorized Service Center, but not by Apple itself.