What is the difference between these watercolor papers?
Gelatin used in paper is made from animal hide cooked down into a gelatin form, while starch is made from wheat and chalk. So for a cruelty-free/animal friendly option, people do prefer to use starch over gelatin for paper-making.
Because starch kind of puts a layer/barrier on the paper, it helps with the watercolor not saturating the paper and absorbing into the paper, which can be beneficial.