Oats ignorant

A couple weeks ago, Eli finished the last of his formula. This week it was the last of the oatmeal baby cereal. So we move on to oatmeal since it still seems he likes mush. But as I perused the "easy breakfast" aisle at the grocery store, I realized, having never eaten oatmeal growing up, I'm very oatmeal ignorant.

What's the difference between oats, quick oats, oatmeal, instant oatmeal and cream of wheat? And are any of them like the baby oatmeal cereal? Which is the kind without the oat seeds or whatever they are called? So I started out with a kiddie instant oatmeal since the "kiddie" label made me feel the most at home even though it probably has a lot of sugar. It says to use water and I can add a splash of milk for creaminess. Can I use milk instead of water?

And how is granola related to oats?

It's clear I have no idea what I'm doing in the oatmeal world. No wonder Tom's dad sometimes looks disappointed when I show him I bought oatmeal just for his visits -- maybe he actually eats something else?