In general, install Windows using the newer UEFI mode, as it includes more security features than the legacy BIOS mode. Comparatively, the MBR is older than the GPT. MBR is another kind of partition table formats. GPT is the abbreviation of GUID Partition Table, which is a standard for the layout of the partition table on a physical hard disk, using globally unique identifiers (GUID). You can prevent this from being created an on MBR using instructions above.
Somewhat comparable to the MBR is with BIOS, but much more flexible and allows multiple boot loaders to co-exist. UEFI is the new replacement for BIOS, the efi is a name/label of the partition where UEFI boot files are stored. What is the difference between EFI and UEFI? The ESP – EFI System Partiton – should not be confused with /boot (not required for most Ubuntu installations) and is a standard requirement. ~300MB should be enough for multi-boot but ~550MB is preferable. Yes, a separate EFI partition (FAT32 formated) small partition is always required if using UEFI mode. In Disk Management, remove that drive letter. USAFRet : The System Reserved should not have a drive letter at all.
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