Sleep watchface in Sleep mode VS Low Power watchface in Battery saver mode

Maybe it is a bit too late to ask it, but let me remark that I surprised even myself  with the fact that until today I had not spotted Sleep watchface in  Sleep mode.

Maybe because I had been using the strategy to switch on both DND and Battery Saver during sleep window and as part of Battery Saver Low Power watchface was opted.

Since Low Power watchface has smaller sized hours and minutes than Sleep watchface has I decided I had to understand what really Sleep watchface meant.

Is it just another design of a normal watchface or is it another type of  special low power watchface?

If the latter is any difference between these two watchfaces in terms of battery consumption?

 

Note: opting for Low Power watchface gives a notification that one can earn as many as 12 days of extra battery, while opting for Sleep watchface does not trigger any info about battery life, so  my bet is that I would not get extra battery life with using Sleep wf vs my daytime basic wf, but who knows.