Thickness

• Both quick and old-fashioned oats are rolled. This exposes more of the oat's center to liquids, leading to shorter cooking times. Oats that aren't rolled, like steel cut oats and oat groats, take longer to cook because the outer layer of germ slows the absorption of liquids. Quick oats tend to be rolled thinner than old-fashioned oats. The thinnest quick oats, like Quaker's brand, cook in just three to four minutes.

Cutting

• Whole oats are either rolled or cut during processing to create a faster cooking final product. Old-fashioned oats are steamed to soften slightly, then rolled to create a thick flake. Quick oats are chopped or cut into small pieces, then rolled to create smaller flakes. These flakes create a creamier, finer textured bowl of oatmeal because of the smaller size of each piece. The cutting process also contributes to the shorter cooking time for quick oats.

Creaminess

• Thicker, more intact rolled oats break up less in transportation and storage. As oats crumble or break, they produce a fine oat flour that leads to a creamier bowl of oatmeal. Quick oats tend to be creamier because they are thinner and smaller pieces of oat. The thicker old-fashioned oats are, the less creamy and more chewy they remain when cooked. Quaker's Old-Fashioned Oats are thinner than other brands, but this variety is still thicker than the brand's quick oats.

Nutritional Value

• There is no recognizable difference in the nutritional value of quick oats versus old-fashioned oats because they are the same exact grain processed slightly differently. Oats don't have their nutrient rich germ or bran removed during any processing done to make them ready for cooking. Eating oats raw leaves the most nutrients and vitamins intact, but both quick and old-fashioned oats can be eaten raw or soaked in cold milk.