The main thing to see is the change of paper: it's crazy how the very light graphite I use to sketch takes on that one!
Actually I always say I use 3 different values in the majority of my artworks, but it's not true: I use 4. The very light value for sketching, and another light one, a bit darker, you can mainly identify here in the shading stage (last one) on the left side, the lower lip, for example.
I still think 3 values as it's what can be seen in the final piece: all the sketched lines are re-drawn or erased.
Anyway, this is the rendering you can expect from now on, I'll be doing some sketching more the usual way only for training purpose, like anatomy. ;-)