An XML file can contain various ‘unattend’ settings for the install such as the Windows Edition (Home/Pro/Ultimate, etc.), Country, Language, disk partitioning details, core components, etc.
The Home or Pro XML files provided by E2B contain generic Windows installation-only Product Keys which are used to force Windows Setup to install that particular Windows Edition.
Most Windows 10 ISOs actually contain multiple different editions of Windows (e.g. Basic/Core, Professional, Ultimate, etc.).
For instance, if you install Windows from a Windows 8.1 ISO, it will not allow you to continue unless you enter in a valid 25-character Product Key. By choosing the correct XML file, we can force Setup to skip this step because the XML file contains a generic Product Key (e.g. for Core or Professional).
Another example: You have a Dell PC which came pre-installed with Windows 10 Home and you have since upgraded it to Windows 10 Pro. Now you want to wipe the disk and re-install a fresh version of Windows 10 Pro – but every time you try, Setup keeps defaulting to installing Windows 10 Home because the UEFI firmware has the Dell Win10 Home Product Key embedded in it’s firmware! So in this case, you can choose a Win 10 Pro XML file and then Setup will install Windows 10 Pro.
Another example: Some XML files contain all the settings to full automate the installation. Setup will automatically wipe, partition and format the target hard disk and then install a fresh copy of Windows onto it. It will then reboot and complete the OOBE setup, add a User Account (with password) and configure any other settings.