Matzo meal is made by grinding unleavened flat bread traditionally consumed during the Jewish holiday of Passover, when leavened products made with grains, such as rye or wheat, are forbidden. Choosing the best matzo meal comes down to what texture is best for the recipe that you're preparing. The meal is available in fine, medium, and coarse textures. Medium meal tends to be the most versatile, but it's best to purchase the type specified for the type of dish.
Leavened foods are forbidden during Passover due to a Biblical story that depicts the Jewish people escaping Egypt so quickly that preparing bread had no time to rise. The symbolic matzo is cracker-like flat bread consumed throughout the holiday, but especially during the Seder dinner. Matzo meal can be ground to form the various textures of matzo meal that can be used to replace grains in standard recipes.
Finely-ground matzo meal is also sold under the name "cake meal" or "matzo cake meal." Use this type of matzo meal if you're making delicate baked goods such as pancakes, pastries, or cakes. Cake meal does make the final product denser than it would normally turn out, so you can mix in a small amount of potato starch to help correct to this problem if you want the baked good to be closer to its original texture.
If a box of meal in the supermarket is simply labeled “matzo meal,” it usually has a medium grain texture. This is the best general-purpose meal to purchase, as it can be used in baked goods, casseroles, and as a breadcrumb substitute to coat meat for frying. Matzo balls, a traditional type of kosher dumpling, are made by combining this meal with broth, animal fat, and seasonings.
The coarsest matzo meal is called matzo farfel. Unlike the other types of meals, which resemble powders or fine grains, farfel comes in chunky pieces similar to larger panko breadcrumbs. This can also be ground down to work as standard matzo or cake meal if those products aren’t on hand. Matzo farfel is best purchased only when a recipe specifically calls for it, as the other meals are more versatile.
Unless you've cooked with matzo meal in the past, it's always best to look up kosher recipes and use the type of meal suggested. It can be hard to predict how a dish will turn out if a different meal is used unless you've worked with that type of meal extensively. Baked goods in particular have a specific chemistry that needs to be adhered to or the final product won't have a proper end result.