But I do understand the difference. And also, when it comes to fs level
snapshotting I would suspect that it would do something we can not do
with the current solutions, for example per-file or per-directory snapshots,
cat ext4 snapshots do that ?

Hi Lukas,

I noticed that there is no answer to this question in the thread.  I
can give the question the answer that ext4 can snapshot per-file or
per-directory, and can exclude some files or directories from being
snapshotted.

-- 
Best Wishes
Yongqiang Yang