NON EMPTY vs Nonempty(): To the Death!

So what is the difference between NON EMPTY and Nonempty()? I've had this question asked several times and have been meaning to blog it for a little while but here's me just getting around to it. So let's jump right in.

We have two queries we're going to take a look at it in order for us to better understand the difference between NON EMPTY and Nonempty(). Behold our first very boring query: