Differential Backup

 Copy only the clusters in files that have changed since the last full backup.

For example, a 1GB file that has only changed by 1MB since the last full backup only requires 1MB of storage in the incremental backup.

If a full backup is not present in the target folder then a full backup runs instead.

Restoring differential backups is often quicker than restoring incremental backups because only two backup files are needed: the latest full and differential backups.