In contrast to Japanese corporate governance, the German executive board has real decision-making power.
[2] It is, by law, the managing body of a company and cannot be instructed by any legal person, be they natural or artificial, to act in such a way as to harm the business.
The exact relationship between the CEO and the other executive officers depends on the company's type, how it was founded, and indeed the individual personalities of the people involved.
It is common practice for board members to be senior executives with specific areas of functional responsibility.
However, the law requires that they oversee the activities of their fellow officers, since they are still personally liable for any failings outside their specific departments/subdivisions.
[1] Formally, the power to appoint executive officers to the board lies with the supervisory board, which can appoint officers with a two-thirds majority vote of approval, or a simple majority if multiple rounds of voting are required in order to reach a decision.