Vault Configuration allows you to Archive a user's Vault data.
For example, if you have live back-up in Vault then this allows you to Archive whatever is also in Vault too.
Archive will only take a snapshot of what is there at the time of the archiving process.
Whereas, Archive Vault will also take everything that's been deleted too and make it easy to view and restore without then paying for an AU licence.
Note, only deleted items are archived from Vault.