They are oats that were not rolled. The ordinary oats, have been steamed, rolled, steamed, toasted, or something like that... That's why they take so little time to cook, because they've already been so much processed.
It's hypothesized that because of the more processing, rolled oats lost some of their flavor and nutrients. That's why steel cut oats are "recommended" (by those who make them of course, the makers of rolled oats recommend rolled oats). People say they also taste nuttier. I didn't really think they taste much nuttier, though.
I just saw them in the store and decided to try them. Now my husband is hooked, LOL, so I either need to figure out how to cook them as to be able to eat them, or cook them for him only. Some people even make them in their crock pots overnight, but I don't have a crock pot (maybe I should buy one...)