Yeah, I mentioned this on GAF but Ill copy paste here. Theres some confusion here, and I have no doubt that they are referring to a very old build that the press was given, which was before the public demo released. Hallmarks of it are the Executioner without the spikes inside his arms/upper body.
Basically, they posted this about the event from December 16th, which features new levels. I had a friend who also played the game at the event and he couldn't spot a difference either, though, as has been demonstrated, its difficult to do that under these conditions, without the aid of direct captures.
The PS3 demo was released in JAPAN ONLY on the 18th. The press was provided with the "new levels" build on the 16th, after the event. I don't think they were given an updated build of the Shanty Town/Public Assembly stage. I haven't seen anything to indicate that.
So basically, the Kotaku guy is comparing the "New Levels" build to the ancient Public Assembly one, with the Executioner who doesn't have spikes on his body.
Or at least thats my speculation. If anyone is in the press, feel free to pipe up on what builds you guys all received.
Edit: To further add credence to this theory, 1UP did a little skit where after the 360 demo was locked out for non Japanese, they realized they couldn't cover it properly. That wouldn't be an issue if they were provided a build before hand.