Huh. The older image on the left looks lower res to me. Or is it that the one on the right has been image processed to the point that features present originally are standing out stronger now? Admittedly, the "new" area does look pretty strong on the right side. However, if I look carefully on the left side, I can see the beginnings of this gully. Also, the original gully on the left looks wider on the right. I wonder if we've got some plate tectonic action shaking things up? Or does this perhaps all come down to orbital inclination? Is the shot on the right from a more "directly above" angle, making small separations more obvious?