I need to earn X amount to pay bills and have a bit left over for the nicer things like restaurants, holidays, new car etc.
I work to get X and once X is achieved I stop work. I have a job!
The businessman needs to do all of above but once he's achieved X he doesn't stop work (like me) and he'll carry on until his working day is over...4pm, 5pm (or whatever) and gets X plus for his extra effort!
Am I on the right track here or missing something?