libzypp, YaST, Zypper, PackageKit and Gnome Software Center - What is that mess all about?

I would like the help of someone with more experience to understand the differences and how those 5 things are connected: libzypp, YaST, Zypper, PackageKit and Gnome Software Center. Here is my take away from a day of research: - libzypp: the backend package management library that powers applications like YaST, zypper and the openSUSE implementation of PackageKit - YaST: it's a system configuration tool that happens to allow the management of dependencies through libzypp. It provides both a graphical interface (GTK) and an interface through the terminal (not sure what it's used here) - Zypp: the official command-line package manager of Open SUSE - PackageKit: that's where things get a little fuzzy for me. This seems to be a package manager abstraction - its supposed to abstract all the differences between apt, zypper, yum, etc - Gnome Software Center: it's a graphical interface (GTK) to install dependencies through package kit - so it's supposed to work with all distros, regardless of the underline package manager used If I understood this correct: - Why don't I see the apps installed through YaST in the Gnome Software Center and vice-versa? - Why would I want to keep Gnome Software Center installed if the previous point (^) doesn't happen? To me this thing just seems cluttered