The Full SD Image is only for people who want to flash a fresh new SD card (all data will be wiped!). Use this file with an image flash tool like Win32 Disk Imager then put the card in your console and it will finalize the process on startup (partition resizing etc).

The Firmware Update should be used to upgrade a previous version of my custom OS but NOT the stock OS. Drop the file at the root of your card then unmount to update.

Visit Drum78 on GitHub for the full documentation.