“Your mission is to become better today
than you were yesterday."
— John C. Maxwell
I think many get the Self-help genre and Personal Development confused. It's easy to do. But, I see them being quite different.
Self-help is where I go if I want to fix something about myself or of a thing or situation. You might classify many of these publications as “How-To" because they often have a solution or series of solutions for problems. In this case, we are beginning with something broken, not working right, not up to speed, lacking, something missing, I need help, I want to get fixed up, I want to change this thing, or the way I do things, the way I live, etc. We're looking for help, in need, desiring change.
Personal Development is very different to me in that it is an expansion from where I am. I am not looking to get help, but looking to learn more about me, the world, other people. I want to expand my knowledge, improve my skills, develop a wider view of life and my place in it. I'm good where I am, but I want to grow. To me, growth is life. It is succinct in one word: expansion. I want to expand.
Another way these two are separated might be stated as need (the word 'help' gives clues here) and desire (the word develop or development is telling)