During the Online Restore process, RMAD restores the GPO folder hierarchy, links and rights in AD via LDAP. Recovery Manager copies All data from backup to SYSVOL via the SYSVOL share. Recovery Manager removes the target folder with the chosen GPO/s (if it exists) and then recreates them from the backup via LDAP.
For example in SYSVOL\\<domain>\\Policies\\<policy folder> the GPO folders are removed one by one as needed, if they exist, and then via LDAP the folder hierarchy is created and finally the files are copied from the backup.
During the Offline restore process Recovery Manager recreates the files in the SYSVOL from backup. This is done via a Microsoft Backup API. More information can be found at http://msdn.microsoft.com/en-us/library/windows/desktop/aa362508(v=vs.85).aspx. No other files in SYSVOL are touched.