Both tasks live in the same little client, both copy files to the NAS, and both show a reassuring green tick. But one of them will faithfully delete your files everywhere, and the other exists precisely to stop that. This is the difference that matters.
Ask a room of NAS owners whether their PCs are 'backed up to the Synology' and most will say yes — while running only a sync task. Then a file is deleted, or ransomware encrypts a folder, and they discover the NAS copied the damage perfectly. Synology Drive Client contains two separate tools that are constantly confused with each other. Here is what each one really does.
A sync task keeps two places identical: a folder on the PC and a folder on the NAS (usually a Team Folder). Edit a file, both copies update. Rename it, both rename. Delete it, and it is deleted in both places. That is not a bug — mirroring is the entire point of sync, because a team must see one shared truth. But it means sync alone offers no protection against the two accidents that actually destroy office data: human deletion and malware encryption. Both travel down the sync connection within seconds.
A backup task in Drive Client works in one direction only: from the PC up to the NAS. You choose the folders that matter — Desktop, Documents, your work folders — and how it runs: continuously, on a schedule, or manually. Files deleted or changed on the PC do not delete the copies already on the NAS, and earlier copies can be restored from Backup Task > Restore in the client. This one-way stubbornness is exactly what a backup is supposed to be.
The healthy setup on an office PC is not either/or, it is both:
When you install Drive Client for a new employee, create both tasks in that sitting. A client installed 'for collaboration' quietly leaves the PC itself unprotected, and nobody notices until the laptop does.
Team Folders keep up to 32 earlier versions of each file, so a file deleted or encrypted through sync can usually be rolled back from its history — that is a genuine safety net, and this series covers it in the versioning guide. But be honest about its limits: versions live on the same NAS as the live files, the count is capped, and old versions rotate away. Versioning rescues files from people. A backup task — and a backup of the NAS itself — rescues you from bigger failures.
Two complaints give the game away instantly:
Neither symptom means Drive is broken. Both mean a task was created by default instead of by decision — go back and choose each task on purpose.
The video walks through creating sync tasks and backup tasks in Drive Client side by side — watch it before you roll Drive out to the whole office.
▶️ Watch Full VideoYes — a local folder can be covered by a sync task (for sharing) and also included in a backup task (for protection). It costs some extra space on the NAS, and for important work folders it is money well spent.
Mostly, yes — the backup task does not pull deletions or changes back down, and copies already on the NAS are not overwritten by the encrypted versions in the same way a mirror would be. Restore after the PC is cleaned. Versioning on the NAS adds a second layer for synced folders.
For office documents, continuous backup or at least a daily schedule is sensible — the right interval is simply 'how much work can this person afford to redo?' If the honest answer is an hour, back up hourly, not weekly.