Jocko Willink positions a leader as one with a high level of authority and a high level of accountability.

If someone has a high level of authority and a low level of accountability – the person is a bully.

If someone has a low level of authority but a high level of accountability – the person is an employee.

Of course, those are general terms, there are plenty of leaders among employees, but only if they take on the authority and the responsibility in addition to the accountability.

Leadership Strategy and Tactics by Jocko Willink