What is the difference between backup and sync?

Sync keeps two locations identical, so a change in one is mirrored to the other, including deletions and corruption. Backup keeps a separate copy with history, so you can go back to how a file was before. Sync is for access, backup is for safety.

Is cloud sync the same as a backup?

No, and this catches people out. A sync service mirrors your changes everywhere, so if you delete a file or it gets corrupted or encrypted, that bad change syncs to all copies. A real backup keeps older versions you can restore from.

Do I need backup if I already use sync?

Yes. Sync is great for access across devices, but it does not protect you from deletion, corruption or ransomware, because those changes propagate. A proper backup with version history is what saves you when something goes wrong.

Backup vs Sync: What's the Difference?

Published: 2026年8月16日

Live answer · Amazon.com

Pulling live prices…

Live data across PricePerGig listings. Prices may change; Updated every few hours.

📊 As of 29 August 2026, the typical NAS on Amazon.co.uk is £160/TB or £0.16/GB across the 3,460 live listings we track, with the widest choice of drives priced around £44.1/TB or £0.044/GB. The best deals on Amazon.co.uk start from about £285 for 8TB (£35.7/TB), £322 for 14TB (£23/TB) and £614 for 20TB (£30.7/TB). The current best value is 14TB at roughly £23 per TB.

Sourced from real discussions on r/DataHoarder and r/backup, cross-checked against live PricePerGig listings.

This is the misunderstanding that quietly costs people their data. They think their synced files are backed up. They are not.

Backup and sync sound similar and even use the same drives, but they do opposite jobs in a crisis.

Sync keeps copies identical. Backup keeps copies safe. The difference matters enormously.

The table above shows the live price per TB on your marketplace for the storage that holds a real backup.

What sync actually does

Let me define it cleanly.

Sync keeps two or more locations the same. Change a file on your laptop, and the sync service mirrors that change everywhere, instantly.

That is brilliant for access. Your files follow you across devices, always up to date.

But notice the trap. If a change is bad, it syncs too.

Delete a file by accident, it vanishes from every synced copy.
A file gets corrupted, the corruption syncs everywhere.
Ransomware encrypts your files, the encrypted versions sync over your good ones.

Sync faithfully copies the disaster to all your copies. That is the opposite of protection.

What backup actually does

Backup works differently, and that difference is the whole point.

A backup keeps a separate copy, usually with history. It remembers how your files looked yesterday, last week, last month.

So when something goes wrong, you reach back to a version from before the problem and restore it. The bad change did not overwrite your only copy, because the backup kept the good one.

Backup is not about access. It is about being able to undo a disaster.

Why this trips so many people up

Here is the dangerous assumption.

People see their files safely mirrored in a cloud sync service and think, great, I am backed up.

Then they delete the wrong folder, or get hit by ransomware, and watch the damage sync to every copy at once. The sync did exactly what it promised. It just never promised to save them.

Sync is for convenience. It is not, and never was, a backup.

How to actually be safe

You want both, doing their own jobs.

Use sync for access, so your current files are everywhere you need them.
Use a real backup with version history for safety, ideally with one copy offsite.
That way a bad change syncs around, but your backup still holds the good version to restore.

Check the live prices above and put a proper backup on cheap storage. It is the copy that actually saves you.

The bottom line

Sync keeps your files identical everywhere, including the mistakes. Backup keeps a separate copy with history, so you can undo a disaster. They are not the same thing, and sync is not a backup.

Use sync for access and a real versioned backup for safety. Grab cheap backup storage at the best price per TB from the live table above, and the day something goes wrong, you will have a good copy waiting insted of a synced catastrophe.

What sync actually does

What backup actually does

Why this trips so many people up

How to actually be safe

The bottom line

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