Sleep differences Whoop vs Athlytic

Hi allI noticed huge differences in restful sleep between Athlytic (Apple Watch) and Whoop. I wore both here for about 10 nights, here are some comparisons:

My subjective feeling is that with Athlytic (I'm using it for years now) the sleep score is always in the seventies and doesn't really indicate how I feel I slept, whereas with whoop it seems to better match how I felt I slept. Also with Athlytic I think I had once 100% and maybe twice 99% in over 2 years of trying to optimize sleep :)The other thing is the difference in "restful sleep". As I understand this is measured by the Apple Watch and Athlytic has no impact on this but I would be interested what others think of this difference?As I learned from the quantified scientist on youtube, the Apple Watch seems pretty accurate in recognizing the different sleep stages. So does this mean Whoop overestimates restful sleep?Also I'm really interested if anybody has more insights on how these different apps calculate the sleep scores? What other metrics are used besides the obvious total sleep and restful sleep. As already mentioned, the Whoop score seems to reflect my subjective feeling pretty good but also seems to not weigh restul sleep as heavy as I thought, because in the data above, I got 85% with 3h35min of restful sleep but on the 17. I got a 99% with only 3h 20min.Looking forward learning more about it...