The difference is that great work is achieved by 1 in one million people. Good work can be achieved by one in 1000 people, or one in 100 depending on your definition. You can adjust your definition of good work to your circumstances. The difference is that even if you are much smarter than average you have miniscule chance to achieve the kind of great work pg tells you about. You can have a high chance to achieve good work, if your definition of good work is realistic.
Yeah, I have some contrarian tendencies, always had, but I am not contrarian in every topic and hopefully not contrarian just for the sake of it.