If I make an ISO with Win10 Pro 14393, make a bootable USB, and use it to create and format the necessary partitions for the installation of Win10 Pro 14393, then I cannot use a similar ISO with 15063 to format the extra partitions once build 14393 was installed. I can only format the main OS partition. In other words I can format all 4 partitions - the Recovery 450MB one, the 100MB one, the 16MB one, and the main one (30.4GB in my case) with 14393 ISO USB, install Win10 14393, BUT if I then load 15063 Win10 USB and attempt to just format those extra partitions - it will not let me format the already created partitions, at least not the 450MB one and the 100MB one. I have to delete and re-create partitions every time I switch builds! Why is that? In each case I used RUFUS GPT UEFI FAT32. Then today I find out that I also cannot restore Acronis True Image (full) backup of Windows 14393 onto partitions created with 15063! I had to delete 15063 partitions, re-create them with 14393, and only then Acronis True Image backup of Windows 14393 could be restored without problems! I only use Acronis True Image bootable USB - never install it as software. In each and every single case partition sizes and formats are identical.