As with the Philly cheesesteak, cornstarch and cornmeal can be also be spelled as two words; I’m using one word for both to keep it consistent.
As simple as these two ingredients are, finding the difference between cornstarch and cornmeal proved more confusing than I anticipated.
I am skipping right over the dictionary definitions of the two, because frankly, they were really unhelpful.
Getting right into it then, cornstarch is derived from the endosperm of the corn, which is what primarily makes up the kernels we eat. Usually used as thickener, cornstarch has about twice the thickening power of flour; they’re often used together in recipes, not unlike baking soda and baking powder.
Cornstarch does not contain much of a flavor other than a bit of starchy-ness, which goes away as you cook it down. Cornmeal, on the other hand, can have more of an actual corn taste to it, which is why it is not utilized as a thickening agent for sauces in the way that cornstarch often is; this is is also why cornmeal is used to make corn-like foods, like cornbread.
Cornmeal is basically dried corn. It can also be called corn flour, although there is technically a difference between the two, which is that corn flour is more extensively broken up. In other words, cornmeal is more of a coarse substance, while corn flour is very fine and powdery.
As EHow.com says, that may seem like a small difference, but cornmeal and corn flour are used differently in cooking. Corn flour, like regular flour or like cornstarch, is used to thicken up foods.
Corn flour is not really a “food in and of itself,” whereas cornmeal, having more substance to it, arguably is a food in its own right. Cornmeal can be yellow or white, or sometimes even blue. There is not much of a difference between yellow and white cornmeal, other than yellow might be just a tad sweeter.
In conclusion, both cornstarch and cornmeal are made from corn. However, cornmeal has more of a corn flavor to it, while cornstarch possesses little more than a starchy taste, and is mostly used to thicken up sauces. Corn flour is basically cornmeal, except more finely ground up.