What are the differences between msys/git and git-for-windows/mingw-w64-x86_64-git?

Question

To be able to run the test scripts for my cross-platform application also on Windows, I installed MSYS2 and used pacman to install any packages my test scripts rely on.

Answer 1

msys/git is linked against a dynamic library provided by MSYS2 to provide POSIX-to-Windows compatibility (POSIX emulation) in a manner similar to how cygwin does (MSYS2 is forked from cygwin), thus it requires the MSYS2 environment to be present to run.

git-for-windows/mingw-w64-x86_64-git on the other hand, is compiled using the MinGW compiler, which performs the translation to native Windows calls at compile time, which results in a much faster binary compared to the emulation approach, and does only require native Windows libraries to run.

From The difference between MSYS2 and MinGW:

The POSIX emulation layer of MSYS2 binaries is convenient, but comes at a cost: Typically, MSYS2 programs are noticably slower than their MinGW counterparts (if there are such counterparts). As a consequence, the Git for Windows project tries to provide as many components as possible as MinGW binaries.

See also: How does MSYS2 differ from Cygwin?