Chromium OS is the open source development version of Google Chrome OS. The operating system is designed to be low resource intensive and community maintainable. It's source code was released under the BSD license.
CrOS vs Chrome vs Chromium
Chromium OS is separate from other projects which might have similar names.
Cr OS - An operating system based upon openSUSE, not related to Google
Chrome OS - A proprietary version of Linux designed by Google, and designed to be installed on commercial Chrome Books.
Chromuim OS - An open source version of Linux designed by Google, built to be lightweight an installed by home users.
Chrome Browser - An proprietary web browser designed by Google.
Chromuim Browser - An open source web browser designed by Google.
Chromium OS is an open-source project that aims to build an operating system that provides a fast, simple, and more secure computing experience for people who spend most of their time on the web.