Last night I developed a craving for shrimp and grits and used white cornmeal in place of the grits (just didn't feel like going to the store.) It tasted okay, but the texture was all wrong. So it seems clear that one difference between corn meal and grits is the coarseness of the grind - is there any other difference? What about polenta? If one is buying bulk ground corn, what should one look for if the goal is grits or polenta?