Your device normally has the internal flash memory divided in 3 partitions, let's call them different disks. The size of the disks differs whether you have 16G or 64G device, so that on both types the size of the MyDocs changes, other disks are always the same size. (unless you change the sizes, of course...) So, on 16G device you have:/dev/mmcblk0p1 ..... (MyDocs) ..... 9G /dev/mmcblk0p2 ..... (root) ............ 4G /dev/mmcblk0p3 ..... (home) ......... 2G On 64G device you have:/dev/mmcblk0p1 ..... (MyDocs) ..... 56G /dev/mmcblk0p2 ..... (root) ............ 4G /dev/mmcblk0p3 ..... (home) ......... 2G Each of these disks are used for different things, and can have different filesystem format. MyDocs is used to store your music, pictures, etc.personal data. home is used for setup data of your applications. root is used for the applications themselves. Normally MyDocs is formatted as FAT32 because that disk can be mounted to an external computer as an USB memory when you connect the cable and select the memory export option. root and home disks are formatted as ext4fs which is more advanced filesystem but cannot be recognized by windows computers.