In the U.S., cornmeal is made by milling dried corn kernels (maize). The corn can be yellow, white or even blue. Most cornmeal sold in U.S. supermarkets is steel-ground (often referred to as "degerminated" cornmeal) but it can also be stone-ground, which retains more of the natural grain. The stone-ground variety is also often organic. Typically, cornmeal comes in coarse, medium and fine grinds. The fine ground cornmeal is sometimes referred to as corn flour. Polenta is made from a fine ground cornmeal (farina d'avena) but often the corn used to make the polenta flour is a special strain grown especially for this application. The corn is also often air dried and stone ground, adding to its cost. There are parts of Italy, for example, that are well known for their high-quality polenta flours. Masa harina is also a fine ground corn but lime is added to the corn kernels before milling.
All of the above forms of cornmeal can be used as dusting agents to help release a pizza onto a pizza stone. However, the forms that are best suited to that application are the yellow cornmeals, mainly because they are the cheapest of all the forms. You can also use polenta flour but since its cost is usually greater than the other forms (about U.S. $4-$5 a pound) it is best reserved for making polenta. I personally wouldn't use a nice organic stone ground cornmeal for that application and I don't see much point to using masa harina for this application, but it can be used if that is all that is available.
I have used all the yellow and white grinds in pizza dough, especially in deep-dish doughs but also in doughs that are to be used to make grilled pizzas. Because matters of taste are involved here, I would use the best cornmeal products I have.