What's the difference between the lights?
 

So it appears there's 3 lights for our cars.

JDM gt86 lights
Subaru's HID with the led surround
USDM FR-S projectors

Is the list above correct?

Is the desire for gt86 & brz lights in the fr-s purely for looks or is there an actual advantage to the light quality/beam between the fr-s and brz lights?

As far as I can tell, the US FR-S projectors seem HIDish, but it seems they are being called projectors, and there's a desire to modify them into HIDs. I'd like to understand. =)

The Scion has halogen projectors. The others have HID projectors. More than that, I'm out of my league talking about.

^^ fly guy is correct, the BRZ/GT86 have HID headlights with LED accent/DRL lighting where as the FR-S has halogen for both, high/low/DRL

I don't even know what warrants using different light sources yet .. I will read into this later though.

first of all gt86 is not JDM

in japan its called toyota 86

gt86 is often referred to as the euro spec.

toyota 86 in japan both has the FR-S halogen projectors (lower spec) and bi xenon projectors with LED (higher spec)

ft-86

Scion Fr-s.