You’re welcome. I’ll try to explain.
In my opinion Kolibri is meant to replace KA-Lite and KA-Lite is still around for backwards compatibility. This comment explains a bit of the difference between the two. Kolibri has the same content available that KA-Lite has, but it also has more updated content for multiple languages across multiple standards while KA-Lite seems to be just for the specific language you choose to install. When you go to install Kolibri content ( channels ) you can pick portions of the content instead of the whole content pack for the entire language. This make it easier to design courses and helps with picking content for each deployment as you can separate by language. It also keeps the size down. Some content in English, some content in French for instance.
To be effective I think Kolibri requires a bit of training for both teachers and students as it’s a classroom management program that requires setting up accounts for the administrator, adding content to courses, and learning how to navigate it. While I think this was available in KA-Lite, it seems much more prominent now. I do think that it’s the best way to future proof your deployment. If you are deploying to Africa soon there’s a better chance that new Kolibri content and updates will be available in the future. I would go with Kolibri as that seems to be their main focus now.
Both KA-Lite and Kolibri run a server in the background. This takes up resources from the system and the Raspberry Pi has limited resources compared to a RACHEL-Plus device which run both, especially on the cheaper hardware like the Raspberry Pi 0w. There are two different images because it doesn’t seem necessary to run both at the same time for the Pi. If you run Kolibri, you don’t need KA-Lite as Kolibri has all of the KA-Lite content available. The Kolibri image was made after the KA-Lite image, and contains a few small fixes. Both images will have all of the same fixes soon when I release a new image ( hopefully this week ).
The issue with the Kolibri image is that you can’t install Kolibri channels from the RACHEL interface. You have to install them from within Kolibri. That is a problem with the finalization script I think. The Kolibri-index module which shows up on the RACHEL home page like other modules works though.
The issue with the KA-Lite image is that when you go to install KA-Lite content from the admin interface, the finalization script errors due to some differences in syntax. This method of installation through the admin interface is probably designed for the RACHEL-Plus and not the RACHEL-Pi and although it works, some of the scripts have things like double  and old file paths for the rachel-pi that don’t work. This is the updated script that works. It is hardcoded to French, ( lang=fr; at the top) but unless another way can be found I’m just going to add a fix in the admin interface to run it for any language.
Networking has changed in Raspbian Stretch and the interfaces file is no longer used. The hostapd settings are in /etc/hostapd/hostapd.conf" and you can see them there. If you’ve run the installation script twice this file might have duplicates in it causing issues. You can edit it with “sudo nano /etc/hostapd/hostapd.conf”. Another thing you can do is “sudo ifconfig wlan0 up” and see if that brings it up. “ifconfig” will show wlan0 if it’s available. Also “iw dev wlan0 info”.
I hope that answers your questions.