In the link you gave it's kind of hard to tell for 360 and XB1 too, but that's partially because there isn't something as readily obvious as a sign in English to use as a reference point like PS3/PS4. If you pay attention to the sand/dirt though you can tell it's way sharper on XB1, so I expect similar for stuff like signs just because there's more ram for sharper textures, even if the framerate is barely better than last gen.
Zooming in on the pictures the XB1 pics ARE subtly sharper, which makes them examples for 720p native actually making a difference. But like I said more RAM means more memory for textures so I think even at the same exact resolution XB1 was going to look much nicer anyway.