What is in a backup.ab file? Using ADB tools for Android (my device had root), I executed the following command:

adb backup -all


After confirming the backup operation, I got a file titled backup.ab that is 350MB. A month later, my device booted with a System UI crash, and would not let me access anything on it. I got a new one (same model), and it is unrooted. What would running the command

adb restore backup.ab


restore to my Android? I want to know what is in the backup (and what restoring it would do), because I want to keep my current userdata. The new device also has a more stable system, so I would not want to restore that, either.

NOTE: This question was marked as duplicate and then ignored, so it has been deleted and reposted.
.ab backups only apps data and their apks as well as system settings.

What is contained:


apks and their data
user vocabulary
wallpaper
launcher settings


What is not contained:


contacts
sms
ringtones and custom sounds
activated input layouts


More detailed is here.