How are Btrfs snapshots different from backups?

Think of a snapshot as a saved view of a Btrfs subvolume at a particular moment. You can use it to recover an older version of a file after an accidental edit or deletion.

It starts out sharing data with the original, so making one is usually quick and doesn't require another full copy. As files change, the old and new versions can take up extra space. A snapshot on the same drive won't save you if that drive fails.

For a backup, put a separate copy of your home directory on another drive. That gives you a way to recover if the original drive dies, not just if you delete something by mistake.

Set it to run regularly and check that you can restore a file from it. Keeping older versions is handy if you don't notice a mistake right away.

One detail that trips people up: a Btrfs snapshot covers a subvolume, not necessarily everything that happens to appear underneath a directory. Nested subvolumes aren't automatically included in the parent subvolume's snapshot.

Before setting up snapshots, check which subvolume actually contains your home directory and whether any important folders are separate subvolumes. A tool configured to snapshot only the root subvolume may not protect your home files.

You don't have to pick just one. Local snapshots are convenient for quick rollbacks, while a separate backup covers problems the local drive can't survive. Both need to be set up before the mistake you want to recover from.