Question about user_backups

[Vpower]

From reseller level I have created a cron that each night takes backup of my users and stores them in the folder user_backup.

When I look in user_backup I see the user.tar.gz files, but also folders named "username".
Example:
user_backup/briiz/
The folder briiz has a sub-folder named backup.
In the folder backup i find:
-bandwidth.tally
-domain.com
-crontab.conf
-email_data
-home.tar.gz
-ticket.conf
-user.conf
-user.usage

what are these used for? Why isn`t the hole backup in the user.tar.gz file?