Among the more common debates I encounter in my work is that of the art of leadership versus the science of management. Each discipline has its proponents, who are (rather unfortunately) mostly concerned about the differences between the two. Champions of leadership sometimes dismiss management as simply making the trains run on time, while proponents of management view leadership as more of an emotional discipline.
The truth is that the best managers tend to be pretty good leaders and stellar leaders know a thing or two (and usually more) about management. I look at it this way: management is the what and leadership is the why. If you have all what and no why, you wind up with a workforce just going through the motions with no real engagement. If you have great why and not enough what, the result is a lot of enthusiasm without much tangible output.