Just to clarify, there are a variety of Oat products out there, here's a list of the type processed enough for human consumption:
Steel-cut Oats (Irish Oats) - oats that've been hulled and cut/halved with a steel blade. They're minimally processed, barely enough to make them edible. They take the longest to cook, and pretty much require you to cook them stove-top for ~30 minutes. They'll have a chewier texture, and sometimes will "pop" when you eat them.
Rolled Oats - Hulled oats that, instead of being cut with a steel blade, they've been pressed flat by a large wheels. They're very flat, and cook relatively fast. You can nuke them in the microwave for 2-3 minutes and have pretty decent oatmeal, or you can cook them stove top. These are your basic Quaker oats.
"Quick" Oats - similar to the above, they're pressed flatter (iirc) and are partially cooked (blanched) so that they cook very, very fast. Tossing them in the microwave for 1 minute generally works well enough. Again, like normal rolled oats, Quaker makes these with "QUICK" written on the tube.
Instant Oatmeal - hulled oat groats that've been milled into powder. This is the stuff that you see in the pre-packaged supermarket variety packs. They're the most processed, and cook ridiculously fast, and are the least healthy for you.