Windows 10 on ARM runs all x86, ARM32, and ARM64 UWP apps from the Microsoft Store. ARM32 and ARM64 apps run natively without any emulation, while x86 apps run under emulation. Microsoft today announced that Windows 10 on ARM will soon add support for x64 apps. Microsoft will roll out the x64 emulation support to Windows Insiders in November.
Emulation support for x64 apps makes several popular Win32 apps available on ARM. This allows users to run existing x64 win32 app without any modifications to the app by the developers.