As per what a Backup of Device is backed up onto a backup account's Google Drive

[a cooperator]

Hi Everyone!
I know that Whatsapp can save a backup file named with "Whatsapp cellphone number backup" onto the Google Drive, daily, when tapping on backup, etc. It can be restored when reinstalling Whatsapp and registering it with the same phone number to which backup is.
However, I dont know when a backup of a device is saved onto Google Drive and when to use it.
Occasionally, I see a backup of my device' named with my phone brand '''LT_M5_lite Backup" is backed up onto the backup account's Google Drive logged in to while the 'Backup & Restore' for 'Backup & Reset' of my phone was turned on, and while reinstalling a app. For instance, when trying to uninstalled and reinstalled Whatsapp, 'backup file' named with my phone brand '''LT_M5_lite Backup" was created onto my Google. I don't know if that backup of device will be created there on my Google Drive if the 'Backup & Restore' for 'Backup & Reset' of my phone was turned off while reinstalling an app or not.

 

[a cooperator]

It'd be highly appreciated if anyone could have had experience with dealing with 'Backup my data', which automatically enable the other option 'Automatic restore' to/and from Google account associated as a backup account?
When does it start backing my data(is when installing or updating apps). I really noticed when did a 'Factory Data Rest', then logged in to Play Store', with my Google Account which was the one setup as the backup account in the 'Backup & Restore' settings.
After that, when some apps got updated, then I found there is a backup file named with this name 'LT_M5_Lite Backup' first part of which is my phone brand name, LT_M5_Lite, which some call it 'Gionee'.

However, I don't know when that backup file can be restored from, and what benefits are there from this setting.