Cooker is the OpenMandriva Lx development branch.
This is where developers do the actual work of developing packages and the distro itself. Because of the nature of this continual work process Cooker breaks at times.
If you are not used to problem solving on computers at a very high level Cooker is not for you.
The Plasma Extended version is basically a complete desktop for most non-technical users. It features software from KDE.org and other Qt based software. It includes software for most day to day tasks.
COOKER Plasma6 x86_64The Slim version of OpenMandriva is for you if you'd like to choose the programs you want to use primarily yourself.
It comes with: the welcome application (OM-Welcome), terminal (Konsole), a file manager (Dolphin), an image viewer (Gwenview), a web browser (Chromium), text editor (Kate, Kwrite), archiving tool (Ark), a graphical program to install packages (Dnfdrake), and of course the well known and feature rich OpenMandriva Control Center.
If you don't wish to have specific software and want a system which has programs for all day to day tasks already installed go with the COOKER Plasma full version.