I guess the difference is that the Gnome overview has been thought out amazingly, has a fantastic search function that actually works, and Gnome takes heavy advantage of their superb implementation of workspaces (virtual desktops).
Gnome doesn't really feel designed for tablets, it feels designed for everything. Hot corners, large click targets, and having good keyboard shortcuts makes it feel good on a desktop, amazing trackpad gestures make it feel at home on a laptop.
Win8 had options scattered everywhere, a search that was just starting to turn bad, and initially did silly things like only let you use one app at a time, no matter your screen size. It was forcing a tablet UX that just felt wrong on a PC.
I think Microsoft were hoping thin and light foldable/tablet devices (that were all the rage at that point) were a good way to sell more windows licenses (thin and lights are weaker hardware so will likely need updated more to keep up with performance demands), hinges are weak points so hardware will be replaced more, all meaning more licenses sold. They were trying to force Windows down this path, IMO. When that failed, they turned to much greater data harvesting, ads, etc.