From the (AI generated?) article…

Steel-cut oats

Steel-cut oats are most closely related to the original, unprocessed oat groat.

Steel-cut oats have a coarser, chewier texture and nuttier flavor than rolled or quick oats.

They also take longer to prepare, with average cooking times ranging from 15–30 minutes.

Rolled oats

Rolled oats, or old-fashioned oats, are oat groats that have gone through a steaming and flattening process.

They have a milder flavor and softer texture and take much less time to make than steel-cut oats, as they have been partially cooked.