Original sentence: Because of the license used by Cygwin's copylefted compatibility library, programs written for Cygwin must be distributed with source code.Code compiled with MinGW uses the Microsoft C library and can additionally use Windows API calls.It is important to understand that these POSIX tools are provided to assist in building an application; they are not intended to provide POSIX functionality to the application when it is run.MinGW forked from the toolchain in version 1.3.3 of Cygwin.MinGW is more an alternative to Microsoft's compiler, and not an alternative to Cygwin.Since MinGW does not provide any POSIX style API other than that offered in the Microsoft C library (functions like open() etc) it is unable to compile some Unix applications that can be compiled with Cygwin.The Cygwin library must either be distributed with the program, or is required to be already present on the end-user machines.Unlike Cygwin, MinGW does not require or provide any compatibility layer DLL
Edited sentence: Accordingly, this approach requires Win32 programs written with Cygwin to run on top of a copylefted compatibility library that must be distributed with the program, along with the program's source code.MinGW aims to provide native functionality and performance via direct Windows API calls.MinGW forked from version 1.3.3 of Cygwin.Since MinGW uses Win32-API calls it cannot provide a full POSIX API; it is unable to compile some Unix applications that can be compiled with Cygwin.Unlike Cygwin, MinGW does not require a compatibility layer DLL and thus programs do not need to be distributed with source code