It's true that hash keys are case-sensitive for normal hashes, but %ENV is magical. 

>perl -e "print $ENV{OS}
Windows_NT

>perl -e "print $ENV{os}
Windows_NT

[download]

Furthermore, the correct usage of Win32::ExpandEnvironmentStrings is Win32::ExpandEnvironmentStrings('%VAR%'). 

>perl -e "use Win32; print Win32::ExpandEnvironmentStrings('OS')
OS

>perl -e "use Win32; print Win32::ExpandEnvironmentStrings('%OS%')
Windows_NT

>perl -e "use Win32; print Win32::ExpandEnvironmentStrings('OS=%OS%')
OS=Windows_NT

[download]

There is a difference between %ENV and Win32::ExpandEnvironmentStrings. 

>echo %VAR%
%OS%

>perl -e "print $ENV{var}
%OS%

>perl -e "use Win32; print Win32::ExpandEnvironmentStrings('%VAR%')
Windows_NT

[download]

Update: Added 2nd and 3rd para.

In reply to Re^2: Win32 GetEnvironmentVariables? by ikegami
in thread Win32 GetEnvironmentVariables? by Anonymous Monk

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