Funny how I read it as saying "His looks better" the first time around, and I was thinking, no, Calamity_Si's version looks better so far.
Upon re-reading it, it turns out Polaris 004's version is fatter
, and I couldn't agree less.
In the concept sketch, the prototype's primary hull appears wider and shorter (from top to bottom), proportionally, like a sports car, or perhaps a sports wagon (you'll see my reason for choosing this as an analogy in due time), which has enough of a width to add to the vehicle's traction, while having a small, short, aerodynamic profile. Overall, it looks leaner and sleeker overall.
The primary hull of the mock-up on the other hand appears to be either taller, thinner, or both. Like a cross-over, it isn't quite as aerodynamic, or especially as low to the ground, or in other words as sleek as a sports wagon typically can be. It looked unrefined, and perhaps had the proportions had come out differently for the mock-up, perhaps the concept might not have been completely abandoned.