Picture 2 is the support bracket on the back side of the engine bay on the firewall. The bracket for the "performance rod" or what we call, "strut brace" has 60% thicker sheet metals. This is also very minor for street car loads but in racing it may be slightly stronger for some tiny handling improvement.

Picture 3 and 4 is the most interesting. The C-Pillar section spot-weld points for jointed sheets, have been greatly increased (11 vs 17 points) to improve structural rigidity, and as result, and combined with #1 above, should improve overall resistance to deformation under dynamic loads in corners, and also reduce load-induced noises and bucking. In production terms, this allowed the car to be sprung with lower pressure gas compression setting for the shocks, enhancing the ride quality and retaining the handling, by resisting dynamic alignment changes of the body, even while under larger loads. Giving the car slightly more mature and refined feel.

Fun huh? Geeky subject perhaps and negligible in terms of real-world differences for most people. But it is one example of how car makers like Subaru and Toyota are constantly drilling at details. There are many more little updates which I might list up as time goes, and if interest is still here with these cars. 

Cheers to all 86/BRZ fans!