They aren't the same. These are 2-verb structures, and you can negate either verb. It's like the Tarantino analogy: having a gun and not needing one, or needing a gun and not having one.
Logically, your two examples can differ, although many people would assume they might not.
Deciding not to go means you don't go, as a result of your own decision. Not deciding to go may mean you were kidnapped, or pressured, or otherwise went without having decided. It's a hair-splitting distinction, but worth exploring for clarity.
Similarly, not enjoying working means she dislikes her job. But she may also dislike time off. Or not. So we don't know whether she enjoys not working.
It is relatively easy to grasp once you have studied Greimassian semiotics. ;)