Microsoft ensures that both 32-bit(x86) and 64-bit(x64) applications are able to run on a 64-bit Windows operating systems. When a 32-bit program run on a 64-bit Windows, a 32-bit emulator will be invoked to handle the 32-bit program. The emulator will make the 32-bit application to think it is running on a 32-bit Windows and the same functionality that is accessible on a 32-bit Windows will also be accessible for the program on the 64-bit Windows.
A 64-bit Windows has two different versions of the program files folder and the Windows system folder (system directory). One version is intended for 32-bit files and other version is intended for 64-bit files.