The image on the right is how the settings app look on macOS 12. On macOS 13 (2022) it was changed to look more to the one on the left, with all the sections selectable in a sidebar and a smaller window. Many users have complained about it, saying that it sacrificed function for form and is part of making macOS more like iOS by mindlessly copying phone UIs onto computers which it isn’t meant for. I think its alright, not terrible. And it’s the norm with settings apps looking like that in Windows, KDE, Gnome, and some other DEs.
The one on the left. To me it is far easier to navigate and looks well designed for its function. The info seems easier to find. Haven’t used the style on the right in years, didn’t even know it still existed so my opinion might be based on what I’m familiar with more than anything else.