I think i've found the difference between Demon's Souls High graphics vs High framerate modes
Here's a shot from the latest 60fps trailer (frame taken from highest quality available)
And here's a shot from the same area, from an official screenshot released a few weeks ago:
Color temperature differences aside, you may notice the first shot's environment ambient shadows are much softer and less defined than the latter, giving the castle a blurrier look. You may also notice some lighting effects are turned up, like atmospheric light scattering, more accurate soft shadows and generally more accurate lighting on the characters (compare detail and speculars on shield).
I believe the people at sony/bluepoint wanted to dispel any rumors about "performance" modes looking bad, so they showed the 4K60fps gameplay knowing we'd be impressed with it, even though they have an even better looking version coming up.