Here are some features off the top of my head that some backups software might have that other don’t, or that you’ll want to consider when choosing or making a system:

• Application aware backups: E.G. DB Backups without shutting down the database. Could also be hypervisor/container awareness.
• Restore: The ability to automatically restore files, systems, possibly to a new location.
• Application aware restore/browsing: Being able to pull individual files from a backup, or accounts from a directory system
• Backup copy: Automatically copying the backup to multiple destinations, disk or S3.
• Retention: Automatically keeping a set number of backups, often including a number of weekly or monthly historical long term copies.
• Backup Diffs: Keeping backups in a way that you only store the data changed rather than a full copy.
• Compression: Compressing the stored data
• Immutability: Keeping backups in a way that allows a (usually cloud) storage provider to lock files for X amount of days to prevent malicious deletions
• Encryption: Encrypting your backups if they’re kept on someone else’s infrastructure or a non-secured area
• Verification: Checking that the backups are intact and not corrupt.
• Control panel: A single place to view the progress and completeness of all backups
• Alerts: Notifications for failed backups, or hooks for successful backups for healthchecks.
• Virus scans: Making sure a backups is malware-free before restore.
• Retries: Ability to retry backups or copies in case of temporary outages before sending alerts

I’m not sure which of these exist in free software, my experience is mostly on enterprise software. A backups system can be as simple as a rsync/zip cron job or a full integrated system depending on what you need.