The main difference is in the nature of the raw material. The MEC clay has no additives, plasticizers, dyes etc. It also has a natural orange to red glow to it when fired thus does not require glazing. Flame ware and ceramic clay contain chemical additives and so in most cases are glazed.
Pure clay is also an excellent retainer of heat so all foods cook in medium heat, and stay warm for much longer. And since the clay is inert, we can safely guarantee that it’s 100% healthy and non-toxic.