What's the difference between Rsync & BTRFS Snapshots

https://linoxide.com/linux-how-to/take-system-snapshots-timeshift/

Timeshift works in two modes: Rsync mode and BTRFS mode.

In the rsync mode, snapshots are taken using rsync and hard links, and common files are shared between the snapshots to save disk space.

In the BTRFS mode, snapshots are taken using the BTRFS file system. BTRFS is supported on only systems having an Ubuntu-type subvolume layout.

https://reddit.com/r/linuxquestions/comments/93dir6/linux_mint_19_timeshift_rsync_or_btrfs/

• BTRFS is a filesystem that needs it own partition to store its backup.
• RSync could save data anywhere, it's more flexible.

I have Rsync option checked in my TimeShift settings, because it is easier to setup than BTRFS— I use TimeShift to restore from little oopsie like theme misconfiguration, wrong package version etc. it's work quite well.

If you required more intermediate case, go for BTRFS then. You're creating a snapshot of your system on the same partition to which you can roll back.

A Btrfs snapshot is done in 1 second. rsync takes much more time. So Btrfs snaps are super handy.

The really main difference is that RSYNC can create snapshots on an external disks. Not the same BTRFS. So, if your need is to prevent an unrecoverable crash of your hard disk, you must use RSYNC. After that using a live boot media (pendrive or DVD) you can install on the live boot media Timeshift and the restore your system from the external difk.