3. Transaction log
A full backup backs up the full/whole database. That backs up all the data.
The full database backup has been done in all the recovery models.
A differential backup only backs up the changed data/extents that were modified after the full database backup has done. The DCM has tracked all the changed extents.
The differential backup has been done in all the recovery models.
Transaction log backup:
A transaction log backup backs up the transaction log file. That is all the modifications/changes.
The transaction log backup only possible in full and bulk logged recovery model.
The transaction log backup is important to minimize data loss and log file size too.
It’s very important to keep the transaction log backup as much as safe, because the restoration needs the sequence of the transaction log backup if, you deleted/missing any one of the backups then you can’t recover the whole data.
It’s good to take a log backup often. It will reduce the log file size and helps to minimize your data loss.