The 1080p upscaler filter on the Xbox One also applies anti-aliasing or some sort of similar technique and effects gamma along with sharpening.
Here is some shots from Killer Instinct running at 1080p on both. When you hit the Home button to go to the dash it removes the filter for a few frames before minimizing into the dash. This allowed me to capture some frames with the game not using the filter.
You can see some comparisons here. Left with sharpen upscaler - Right with nothing applied. Both captured from 1080p source.
I will post some more comparison screens on Tuesday when I receive Dead Rising 3, Battlefield 4 and Call of Duty Ghosts.
I posted more about this here -
http://www.neogaf.com/forum/showpost.php?p=91733203&postcount=190
Notice on the right screen with no filter applied in the background on the wooden beams how much aliasing is shown but it's not seen at all on the filtered screen.