What's the difference between rolled oats and old-fashioned oats?

The main difference between rolled oats and old-fashioned oats is in their texture. Rolled oats are flatter and thinner, while old-fashioned oats are thicker and have a chewier texture. Both types are made from whole oat groats that have been steamed and rolled, but old-fashioned oats are rolled thicker, giving them a heartier texture when cooked.