Okay, so I seem to be a tiny bit . . . wrong . . . about polenta being a form of Italian grits.
I blame my grandparents. They used ground-up cornmeal for the dish they called grits, but apparently grits are made from ground hominy. Polenta is made from cornmeal mush, and it’s stirred a LOT longer–30 minutes, by hand. About.com has a good article on the subject with some interesting recipes as well. While grits are generally the consistency of oatmeal, polenta is usually much firmer.
Both foods have the distinction of causing pellagra (niacin deficiency) if you try to survive on them exclusively, as poor people in northern Italy and the southern US used to do. So that’s one thing they DO have in common.
Paul, I hope this helps answer your question.