System-level snapshots take full copies of the whole instance on which your database is running. This results in the snapshots being “heavy”. Because they contain a large amount of data, they can require a lot of compute bandwidth and time to complete. When restoring, point-in-time restore is not an option as transaction logs are not available.
Database-level backups start with one full copy, and after that, scheduled incremental backups of the database are added. Additionally, transaction logs can be backed up, which enables point-in-time recovery. This overall process is much lighter weight and increases performance and retrievability.