Since the 2014 WRX in Crystal White Pearl is basically Halo, I took some pictures on my phone (a 5s) but I don't know if you guys will be able to tell the difference. In a physical perspective, Satin White Pearl (Whiteout) pigments reflects more green & red light, and Crystal White Pearl pigments reflect more blue & red light. However, this is more noticeable from further away and it's dependent on the angle of view. The best way to tell the difference is to look at how the white differentiates as you look toward the rear door to the front fender.
Crystal White Pearl (Top)
Satin White Pearl (bottom)
