Blah okay. Huge file b/c of the tiny, almost illegible handwriting.... sowwie.
Anyway, the tutorial explained a bit more in depth:
I've noticed people have trouble with blending or think there's only one way to do it. Well, it really depends on what texture you're trying to render. For example, the airbrush is really good for skin, and the water tool is really good for gradient backgrounds or misty/foggy areas.
The blur tool isn't used as much as others b/c it can leave your painting looking too blurry and without depth. And like I stated in the tutorial, the airbrush is definitely the most versatile.
So hopefully this tutorial highlights the differences between the tools.
If you have any questions, feel free to ask. I answer all questions as thoroughly as possible (:
K, tbh I made this b/c I've been up all night and couldn't sleep xD