Cornmeal and masa harina are very different preparations of corn. “Masa is usually white and has the consistency of wheat flour, whereas corn meal is often times yellow and is like micro couscous,” says porker. “Masa harina is made from white maize flour treated with lime or wood-ash lye,” says Sam Fujisaka. It’s good for making things like corn tortillas and tamales. “I use corn meal to make corn bread; but corn meal does not make tortillas,” says Sam Fujisaka. “I also make corn bread using the meal people here use to make arepas: Areparina makes good corn bread but is not good for tortillas!” danhole adds, “you can use corn meal for polenta, but you can’t use masa harina for it.”
You can also get finely ground cornmeal the consistency of flour, but that hasn’t been treated with lye like masa harina. Veggo likes this kind of fine-ground cornmeal as a dredge for frying oysters, shrimp, and fish when he doesn’t want the gritty texture of cornmeal. You could probably make tortillas with it, says Sam Fujisaka, but they wouldn’t taste the same as tortillas made from masa harina.
Board Link: Corn Meal vs Masa Harina