C# - Environment.Is64BitProcess vs. IsWow64Process()

It returns true if the current process is a 64-bit process (running on 64-bit Windows).
I.e. the program was compiled for 64-bit, is running as 64-bit, on a 64-bit operating system.

It returns true if the process (identified by process handle) is a 32-bit process running on 64-bit Windows.
I.e. the program was compiled for 32-bit, is running as 32-bit, on a 64-bit operating system, but in a 32-bit-to-64-bit compatibility layer called Wow64.

Wow64 stands for Windows-32 on Windows-64;