There is always less data included in an incremental backup than a full backup.
That statement is correct. An incremental backup is a backup method that only includes the data that has changed since the last backup, while a full backup includes all the data on the system being backed up.
To understand why there is always less data included in an incremental backup, it's important to know how incremental backups work.
When an incremental backup is performed, only the files that have been modified or added since the last backup are included in the backup set. This is done by comparing the timestamps and attributes of the files with the previous backup. If a file has changed, it is considered "incremental" and is included in the backup. If a file has not changed, it is skipped.
This means that an incremental backup only captures the changes or additions made to the data since the last backup, resulting in a smaller backup set compared to a full backup. The size of the backup set will depend on the amount of data that has changed since the previous backup.
The advantage of using incremental backups is that they take less time and storage space compared to full backups. However, a restore process that involves incremental backups may be slightly more complex, as it requires restoring multiple backup sets in the correct order to fully restore the system.