Cornflour is a finer grind than cornmeal. It is used in making softer breads, such as tortillas. Cornstarch is a super fine grind, and it is often used as a thickener or binder in cooking. In some countries, such as the UK, cornflour is not widely available, and they refer to cornstarch and cornflour. It is important to know where your recipe comes from to avoid confusion of ingredients.