Android not touched, only updates the area with second operating system on it, so you're going from OpenELEC to LibreELEC, but Android untouched. If you see them around 100-200Mb, likely to be a big partial update or just second OS.
Backup important data first, but if Kodi 16 is critical in 2nd OS worth a punt. If you'd prefer for other to test and it to become official (hopefully), no problem, obviously.