Managers vs Leaders

What are the difference between managers and leaders? Are they interchangeable or are they the same thing? Are all managers leaders or vice versa? I know that these seem like a lot of questions but for me it was something that I really wanted the answer to. Our school book talks about the difference between leaders and managers, and I also found an interesting article that delves deeper into the subject.

This Article was on the Changing Minds website and it entitled Leadership vs. Managers . I found that many people can be both leaders and managers, but just because you are a manager does NOT mean that you are an automatic leader. Leaders have characteristics such as "they focus on vision, mission, goals and objectives" while managers" see themselves as preserves of the status quo" (Chuck Williams, MGMT, pg 253)

This article also talks about how managers have subordinates, while leaders have follows. With a manger, you don't choose who your manager is, you have to be their subordinate. However with a leader, they don't necessarily have to be "above you" in your job, they can be a co-worker that is at the same level as you, and they could still be a leader.

I have found through my different jobs, that the best managers I had were also natural leaders. I think that being a leader is very important in being a manager, do you agree?