To Manage or To Lead? That's the Question!

I know a guy who is dealing with management as well as leadership.  What are the principles?  Are they the same?  How do they differ?

I asked a few people and got some helpful responses.

Here's one from an article called Leadership and Management by Steven R. Covey

You might also like this one Manager or Leader

And then there's this one Leadership of People

I'm adding these to my list of other resources to help me get a clue.