These packages often contain only "differential" data, meaning the file size is much smaller because it only includes what has changed since the last version rather than the entire operating system.
The most interesting feature regarding this file format is its capability: AB-GOTA.zip
The system maintains two separate partitions (A and B). While you are using partition A, the AB-GOTA.zip file installs the new update to partition B in the background. You only experience a brief restart to switch to the new version. AB-GOTA.zip
If the update in partition B fails to boot or is buggy, the system automatically reverts to partition A. This prevents the device from becoming "bricked" during a failed update process. AB-GOTA.zip