Linux + GNU Tools + KDE/Gnome make a Linux OS. These are the parts of almost...

Linux + GNU Tools + KDE/Gnome make a Linux OS. These are the parts of almost all Linux distros around.

Though there are other distros which differ such are Glendix and SkyOS.

Glendix is implementation of Plan9 tools on Linux.
SkyOS though not ready yet will be using Linux kernel.
Also ChromeOS might be different.

One thing common in all these is Linux kernel :)

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