Manager vs. Leader
The book the 7 habits of highly effective people clearly describes the difference between management and leadership. Management is putting first things first, organize and control. Leadership decides what those first things are. A leader has a clear vision and can inspire people, while a manager is controlling a process. A manager is organizing how and when something is done, while a leader takes care about what and why things are done.
Leadership needs management
Leadership needs management and the other way around. A manager with no leadership skills would be an annoying boss. But a leader who is not able to manage is even worse. Mintzberg argues that leadership and management need to fit together in one role. An organization needs managers who can lead.