GPT is the GUID Partition Table. MBR is the Master Boot Record. Both are mechanisms for dividing hard drives into partitions.Windows 10 Product Keys are codes that are used to activate Windows 10. Windows 10 Product Keys are normally located on the underside of your laptop or on the side or back of your desktop PC. If you bought a digital copy of Windows 10 from Microsoft Store, you will find the product key in your Microsoft account.