A Full Backup is the most common type of backup performed. It backs up the entire SharePoint Farm for disaster recovery, media failure, or data corruption across many content databases or site collections.
Full Backups consume more space and time per backup and are typically supplemented by Differential Backups, which are created more frequently. With Full Backups, you can re-create a SharePoint Farm in one step. To do so, you can restore the entire farm or you can restore an individual web application or content database from the same Full Backup.
The entire SharePoint Farm is backed up during a Full Backup even if individual web applications or site collections are selected on the NetVault Backup Selections page. A Full Backup does not depend on any other backup and can be restored in a single step.
With a Differential Backup, only the data that has changed since the last Full Backup occurred is backed up. Differential Backups reduce your risk of data loss because they are smaller and faster than Full Backups.
A Differential Backup is useful if some of the site collections are modified more frequently than others. In this case, Differential Backups let you back up frequently without the overhead of Full Backups.
A Differential Backup must always have a “base” backup, which is a Full Backup. Performing a Differential Backup without first performing a Full Backup may lead to backup failures in addition to an inability to restore and recover your SharePoint Farm properly.
Individual Site Collection backups are an ideal option when you only want to protect a subset of individual site collections or duplicate one or multiple site collections to a test environment. Individual Site Collection backups are independent of an established sequence of backups and do not affect the recoverability of Full or Differential Farm Backups. However, they should not be used as a replacement for a Full and Differential Backup strategy.