Sync folders propagate mistakes. Backup keeps history. Here is the practical difference — and why an encrypted one-way mirror is the safer default for irreplaceable work.
Three private surfaces. Same zero-knowledge architecture.
**Sync** keeps two locations identical. Identical includes your mistakes: a deletion, an accidental overwrite, an encryption pass by ransomware. All of it replicates, usually within seconds.
**Backup** keeps a history. The remote copy is a record of what existed, not a mirror of what exists.
Versioning in mainstream sync tools mitigates this partly, with limited retention and limited coverage of bulk events.
Three private surfaces. Same zero-knowledge architecture.