[Nonfractal]

They are different bodies between the two, clearly. If you look at where the radiator openings start on each model, the Scaleauto starts at the back of the drivers seat. The NSR starts at the drivers elbows with arms on the steering wheel. Quite a bit different. And then there's the different noses and front and rear wings. Yes, of course they look similar, they're both F1 cars from nearly the same era!!

Look closely, the chassis on the scaleauto is deep chamfered to give that shortened side pod look.
This may prove to be a design mistake because it might be a weak point in the chassis where it will bend and break. 

The NSR chassis does protrude further forward so body with a shorter side pod would leave the chassis protruding.
BUT, not all cars from that period were truncated like that.
The 1990 mclaren had a rounded pod face and there is no body protection on the scaleauto chassis for a body designed like that. 

AND.. who cares if the chassis protrudes beyond the body?
All modern slot cars are flat plate chassis that protrude beyond the body. 

NSR have the opportunity to design  modern bodies for the 8689 chassis. 
Hopefully they can make it prettier