I'm not intimately familiar with the UI/UX principles behind Liquid Glass so I could be wrong, but the main difference I see here is that in the second screenshot, on the Reeder app on the left, the "floating" section is used for emphasis on the main content area (right hand side), while in the Finder screenshot on the right, it's the navigation menu on the left that is floating, and brings unneeded emphasis to itself.
Looking at it for 30s, I still don't understand what Apple was trying to do. What am I supposed to believe happens to the table as it goes under that floating menu? It clearly doesn't seem to continue all the way to the left edge of the window. Why not? If not, why bother with that whole floating menu concept if the underlying content arbitrarily stops at the menu?
The most surprising part to me is how people keep calling that nonsense "skeuomorphic" when it doesn't replicate any kind of physical intuition known to mankind. It's just made up physics that looks dumb.