John Kotter’s work deepened and extended insights into the distinction between management and leadership. He advocated they were complementary systems of action, both necessary for success, but that most companies were over managed and under led. Good management is about coping with complexity and bringing about a degree of order and consistency. Leadership is about coping with change in a dynamic environment.
I would add that management tasks can be delegated whereas leadership is a personal responsibility. Leadership is about influence; management is about control.