Backing-up is a crucial process that everyone should do in order to have a fail-safe, for when the inevitable happens. The principle is to make copies of particular data in order to use those copies for restoring the information if a failure occurs (a data loss event due to deletion, corruption, theft, viruses, etc.)
The differential backup contains all files that have changed since the last FULL backup. The advantage of a differential backup is that it shortens restore time compared to a full backup or an incremental backup. However, if you perform the differential backup too many times, the size of the differential backup might grow to be larger than the baseline full backup.
Full backup is the starting point for all other backups and contains all the data in the folders and files that are selected to be backed up. Because the full backup stores all files and folders, frequent full backups result in faster and simpler restore operations. Remember that when you choose other backup types, restore jobs may take longer.