John Kotter of Harvard Business School argues that leadership and management are two distinct, yet complementary systems of action in organizations. Specifically, he states that leadership is about coping with change, whereas management is about coping with complexity (Kotter, 1987)  Management is the concrete, perhaps more left-brain action of planning, organizing, and efficiency, while leadership is the abstract creation of vision and strategy and inspiring others to turn the vision and strategy into reality.

Leadership FunctionsManagement Functions
Motivating and InspiringOrganizing
Creating or changing systems and behaviors to produce much better outcomesControlling