Thick-rolled oats are large whole flakes, and thin-rolled oats are smaller, fragmented flakes. Rolled whole oats, without further processing, can be cooked into a porridge and eaten as old-fashioned oats or Scottish oats, but more highly fragmented and processed rolled oats absorb water much more easily and therefore cook faster into a porridge, so they are sometimes called "quick" or "instant" oats.
