Original: VistaPE uses technology from and largely resembles Windows Preinstallation Environment 2.0 (from Microsoft), but has a graphical shell, expanded set of supported devices and functions, and can run almost any Windows program.
Simplified: VistaPE uses technology and is similar to WinPE 2.0 (from Microsoft), but has a graphical interface, more support for devices and functions, and can run almost any Windows program.