Greddy RS vs RZ BOV??

[Maj3sticCr0w]

What is the difference other than about $100? Is the RZ just the new model? I know Phat has the RZ in stock but there is a place in Perth selling the RS for $299. I think the colouring is different as Ive seen the RZ in dark grey and the RS in stainless and metallic blue (would rather the stealth look). Just wanted to know if there was any technical difference?