Help with formatting flash drive

[spiritech]

i need some help regarding the disks utility. first i would like to ask. what is the reason for the two formatting options, the one in the top right and the one just below the Volumes box. one gives the option to format (mbr/dos) or (gpt) or no partitioning (leave empty) and the other gives the normal formatting options such as fat32, ext3/ext4 etc. in what case do i need to use the first options and if so which one is recommended.

secondly i am trying to parition a flash drive and keep getting errors. it says the content of the drive is Unallocated Space (GUID Partition Table). if i try to use one of the (mbr/dos), (gpt) or (leave empty) options i get this error

Error synchronizing after initial wipe: Timed out waiting for object (udisks-error-quark, 0)

if i try to format a partition i get this error

Error creating partition on /dev/sdc: Command-line `parted --align optimal --script "/dev/sdc" "mkpart \" \" ext2 1MiB 16240328191b"' exited with non-zero exit status 1: Error: The primary GPT table is corrupt, but the backup appears OK, so that will be used.
Error: Unable to satisfy all constraints on the partition.
 (udisks-error-quark, 0)

i really dont understand the two formatting options and/or when to use them. the only thing i can gather is one is table format and the other is partition format.

spiritech