Hello @Mega_Print !
OctoKlipper and Klipper are basically the same.
OctoKlipper is a OctoPi/OctoPrint with a Klipper installation, where OctoPi is the OS and OctoPrint is the web interface.
Klipper itself is the firmware solution, that can come with Moonraker and Mainsail/Fluidd
For a better understanding you may have a look here: