sophos xg : "Backup configuration" vs "Export full configuration "

Backup contains sensitive data. Export does not. 

hello 

what sensitive data do you mean ? 

when I import full export , XG asks me my master key to import sensitive data, so export contains sensitive date

for example I can import authentication servers from another XG with all credentials.

But you cannot export privat keys in certain cases like CAs or other options. 

Most likely i would not recommend to perform a Export/Import for a backup/Restore scenario. If you have a new appliance and want to restore your current configuration, use Backup/restore. 

If you want to copy paste certain configuration options, but create a new firewall within your setup, use export/import.