ReactOS is a free and open-source operating system for x86/x64 personal computers intended to be binary-compatible with computer programs and devices. Developed by Aleksey Bragin
License: Open Source
FreeBSD is a robust, Unix-like operating system known for its stability, security, and advanced networking capabilities, making it ideal for servers and advanced users. In contrast, ReactOS is an open-source operating system designed to be binary-compatible with Windows, focusing on providing a familiar environment for users transitioning from Windows, but it is still in development and thus may lack the stability and features of more mature operating systems.