When databases are set to full recovery model in SQL, Intronis Backups take full backups instead of true differential ones.
Intronis Backup Intelliblox technology allows block-level differentials on previous backups, but copies all of the SQL transaction logs every time a backup is performed, creating larger files. Full recovery mode specifies that all database transaction logs are saved so that you can restore to very specific transactions in the database history.
The recommended configuration is to set your databases to simple recovery mode in SQL, which will allows backing up smaller files and ensures that the transaction logs are truncated each time a checkpoint is issued for the database. This means that your daily differential backups are much smaller. However, simple mode does not have the same level of granularity to restore specific points in database transaction history. To read more about this, please review this KB article on simple recovery model.