Librewolf is more focused on privacy by removing all the phone home stuff and strong enhanced tracking protection / resist fingerprinting. Floorp also has those things enabled, not quite as strong as on Librewolf so that websites function (but you can change the settings anyway), while it also extends the browser more generally with a special focus on the UI. The tab bar looks good again. You can place any toolbar at the bottom of the browser. They integrate a few extensions such as Tree Style Tabs, workspaces, an extended sidebar that includes web panels, and they restore compatibility with some of the older XUL addons.

I'm not sure it's exactly the same, I think this is actually prettier. And more customizable. You can put the tab bar at the bottom with Floorp.