The difference between leader and manager

Abraham Zaleznik wrote in an article from the Harvard Business Review in 1977:
"The difference between managers and leaders, he wrote, lies in the conceptions they hold, deep in the psyches, of chaos and order. Managers embrace process, seek stability and control, and instinctively try to resolve problems quickly - sometimes before they fully understand a problem’s significance. Leaders, in contrast, tolerate chaos and lack of structure and are willing to delay closure in order to understand the issues more fully in this way, Zalenznik argued, business leaders have much more in common with artists, scientists and other creative thinkers than they do with managers. Organizations need both managers and leaders to succeed, but developing both requires a reduced focus on logic and strategic exercises in favour of an environment where creativity and imagination are permitted to flourish."

Warren Bennis, in his book "On Becoming a Leader", writes what he considers the differences between managers and leaders:

-The manager administers; the leader innovates.
-The manager is a copy; the leader is an original.
-The manager maintains; the leader develops.
-The manager focuses on systems and structure; the leader focuses on people.
-The manager relies on control; the leader inspires trust.
-The manager accepts reality; the leader investigates it.
-The manager has a short-range view; the leader has a long-range perspective.
-The manager asks how and when; the leader asks what and why.
-The manager has his or her eye always on the bottom line; the leader has his or her eye on the horizon. The manager imitates; the leader originates.
-The manager accepts the status quo; the leader challenges it.
-The manager is the classic good soldier; the leader is his or her own person.
-The manager does things right; the leader does the right thing.

I showed my friend an article on Bennis' book and we both agree that work involving developmental, creative processes need leaders; while work that go by set standard procedures require more management. My friend is now a bit enlightened though he still wonders how their management can steer their projects full steam ahead from their drifting position.