Looking at the ingredients/description on the website, the difference seems to be that the "instant" rice is precooked. However, like the previous post mentioned, companies do some shady stuff that lets them claim that a more processed product is still "whole grain". Even if nothing is removed, the grains are likely cut up more to increase surface area, which would marginally raise the GI. Assuming that parts of the grain haven't been removed, this difference would be minimal and certainly not something to worry about given that you're eating it with protein/fats, which will slow digestion and reduce the insulin response anyway.