The difference is that normally, the CEO answers to the board every few months. And the board doesn't tell the CEO what to do; the point of a CEO is that they can be trusted to do the right move. If they can't, then they serve no purpose and will be fired.

In this structure, Elon is embedded in the decision making loop directly. The CEO normally is responsible for the company, but instead, Elon has decided that the CEO will deal with making money while he makes all of the decisions as to how the product works. Which essentially cuts the CEO of of any decision making aside from business partnerships, making her more of a VP of Sales than CEO.