The difference is minimal, in the newer version you have 1 less element when the sidebar is collapsed (the hamburger menu).
Generally speaking Gnome 44 is already well optimized, 45 is going to be a more “tweaks and small improvements” kind of update rather than a big design changes
but …surely you could just do the same thing with the old design? artist’s rendition:
in fact, now i look at it, it makes them look even more similar once i collapse the sidebar
The difference is minimal, in the newer version you have 1 less element when the sidebar is collapsed (the hamburger menu).
Generally speaking Gnome 44 is already well optimized, 45 is going to be a more “tweaks and small improvements” kind of update rather than a big design changes