I think you are right. In the presentation, Frank from Naughty Dog says the images shown at the panel have perfect lighting. Here is what he says: "I want to remind you guys. This is what we call a staged lighting room for the characters. Basically, this is basically like a perfect lighting for us to show off our model. But you guys might notice in game, there will be different lighting situations, you probably won't be able to see all the detail he has under those situations."
So basically, while the model is the same, the lighting is not. In the panel, they said this time around most of the detail is in the shaders and not in model. Since they showed they have the ability to scale the detail on the shaders, I think that is what they are doing based on different situations in the game. Naughty Dog showed the model going from looking like plastic to looking very realistic just by changing the level of detail on the shaders.