I dont see the difference between 30fps and 60 fps.
Make sure you select the "Settings" gear and chose an HD resolution that says 60 FPS to ensure you can even view 60 FPS first.
If you already did this, know that there is a difference, not everyone may notice it, however this
IS NOT true 60 FPS, but instead interpolated, which means that the movie was "rendered" in a way with more frames, essentially frames were created in-between existing frames to give the illusion of more detail in the video.
I recommend looking up "
motion interpolation" for more information on the subject.
Regardless, the difference is very subtle in this case, and is hard to really notice, due to the nature of how motion interpolation works. Try looking at combat scenes to get the fullest effect of this FPS "increase". Instead, I would recommend you actually look at real comparisons between 30 FPS and 60 FPS games and imagine how it would look for this game, as motion interpolation is NOT real 60 FPS.