Full

When the Level is set to Full all files in the FileSet whether or not they have changed will be backed up.

Differential

When the Level is set to Differential all files specified in the FileSet that have changed since the last successful Full backup of the same Job will be backed up.

If there is no successful previous Full backup, a Differential backup is upgraded to a Full backup.

Incremental

When the Level is set to Incremental all files specified in the FileSet that have changed since the last successful backup of the the same Job using the same FileSet and Client, will be backed up.

If there is no successful previous Full backup, an Incremental backup is upgraded to a Full backup.