Non-Intel Macs won't support this bootable standard, hence the only option available to them is the Apple Partition Map (APM). As part of the Unified Extensible Firmware Interface (UEFI) standard, GUID is a bootable standard for systems with EFI firmware such as macOS.
This is a standard for the layout of the partition table on a storage disk using globally unique identifiers (GUIDs).
Clean 500MB of Junk for Free GUID Partition Map
