"Becoming a Manager" by Linda Hill is a classic book on this. She followed several (18? 19?) new managers through their first year as managers and provides a lot of insight into the difference between "doing" and "managing." The book was originally published about 10 years ago, but there is a new, updated edition out recently. One of her conclusions in the updated edition is that managing is harder now than it used to be. Globalization and rapid change have made the process more complex. Published by Harvard Business School Press. Available from your local bookstore.