Maybe I'm not as critical about the UI, but I have both browsers open at the same time so I took a second to compare them.
Both browsers have a row of tabs. Below that is a second row. The left most set of buttons is navigation (back, forward, refresh, etc), then the address bar, then on the very right of the row is a set of buttons for extensions, settings, etc. The remaining portion of the window is the webpage. I'm just not seeing many differences. The view of recently downloads is different, but nothing that bothers me from either one.
I also just compared how both browsers displayed HN main page. Slight differences in color of orange and font weight, but only noticeable if comparing both directly (and besides devs, who does that?).
So I guess I'm asking what about the UI/UX is bothering you. I'm almost hesitant to ask because I'm sure if you point something out that bugs me, I'll never un-see it.