Okay, the chassis parts break-down are about the same in both kits. Again, Tamiya gains the edge in fidelity and refinement of molding. Here is the Tamiya chassis.

notice that the bottom of the turbo and such are present in the engine bay. Also, Tamiya molded the gas tank to the chassis. Fujimi chose not to.

Notice that none of the turbo plumbing present in the Tamiya chassis is included in the Fujimi chassis. Also, as mentioned before the gas tank is a separate piece on the Fujimi chassis.
Here are the remaining Fujimi undercarriage parts. Fujimi chose to mold the rear end as one solid piece while Tamiya chose to mold them separately. Fujimi, while molding the brakes to the struts, did a beautiful job with these. There are delicate holes drilled into the rotor faces, while the tamiya brake rotors are smooth.



In the last photo, you can see the Tamiya dash. It is very nicely molded as are the rest of the interior parts. Interestingly enough, both manufacturers chose to include both left and right handed dashes and consoles. Here are the Fujimi dashes. Both make use of decals for instrumentation. Fujimi gives both dial and digital faced clusters, while Tamiya includes just dial faces.

Okay, so there we go. Two kits representative of the time period of each company's work. I think that Fujimi has made large gains in equalling Tamiya quality. I believe that Tamiya has made even bigger gains in fidelity and engineering of their molds. I also think that it really depends on from what time frame the mold comes from. Some of the much older Tamiya stuff is no better than the Fujimi stuff of the same time frame. In all, Fujimi does have some good points as they tend to do kits that Tamiya does not. If you have a choice though, between a Tamiya kit and a Fujimi kit of the same offering, go with the Tamiya... Now treaded and winged thingies are a completely different story.