That is a good question, why is Windows 8.1 x64 bigger than x32 on HD and Greater on DVD?
This is because the x64 supports also the x32 eg. x86 Software via WOW (Windows on Windows) subsystem.
But this is not only in Windows 8 x64 so, but also on Windows 7 x64 and on the new operating system Windows 10!
FAQ 232: Updated on: 11 June 2019 11:04