Yes, the difference is you didn't write that code. I thought that would save time but it has proven to make debugging difficult.
yep, jQuery and other js frameworks are designed to basically save coders' time in a production environment where you are routinely churning out web pages with js functionality.
To be honest, I have hardly ever used jQuery - mainly because in my particular circumstances I don't need to use a js framework to do what I want. Over the years I have built my own js library of "common" tasks/functions and I just tweak them to suit particular situations where needed.