Without this earned authority (that is, authority beyond title), you lose a lot more than you gain. Employees who work from fear will lose the will to put in extra effort, and confidence to suggest how to improve processes. Employees who are truly talented are more likely to leave for a position with leaders that make them feel respected, leaving the boss with the worst employees (which was actively occurring with the previously discussed boss).
The most important difference might well be behavior. A leader models the desired behavior, a boss will not. This leads to an interesting truth. Anybody can be a leader whether or not they hold the title.