

Exactly. A backup tool makes an entire copy of a filesystem. A time-based snapshot tool only covers the delta of changes to the filesystem.
So if you want a fully functional copy of your filesystem, then you make a full or incremental copy.
If you just want to be able to “rewind” to a point-in-time version of it, then Timeshift or snapshots allow you to do that.
It’s not Silverblue specific, it’s the Linux Kernel.