Management consists of doing things right and leadership consists of doing the right things… (paraphrased from Bennis & Goldsmith, 1997, p. 4). I infer from this statement that both management and leadership present as modes of directing behaviors of self and others. People appear to most appropriately use either of these constructs in contextual situations. Management also appears to best apply in non-emergent conditions, where clear standards and procedures exist. The goals for management likely include achieving efficiency and effectiveness, based primarily on those contextual standards and procedures. Conversely, leadership appears to best apply in emergent conditions, where clear standards or procedures do not exist. The goals for leadership likely include mitigating loss and maximizing gain.
In the literature, some have described leadership as having only to do with functional positions of authority. Others appear to have discounted that notion (e.g., “all leaders manage, but not all managers lead”). In Western cultures, typical organizations arguably hire managers to fill hierarchical positions. They further seem to expect only those managers to lead at the appropriate times. Even if the associated hierarchies would welcome leadership from "the masses," many have presented structures designed to withhold leadership authority from anyone other than managers. This seems to contribute to two major concerns: (a) if, in situations lacking standards or procedures, subordinates present greater functional expertise (operative, coordinative, or strategic) than those in hierarchical positions "above" them, the subordinates should arguably serve as leaders, at least until the entity establishes standards and procedures. My observations indicate that sometimes this doesn’t happen and for several reasons (lack of trust, face-saving, et. al.), and (b) those with hierarchical authority can arbitrarily act as a leader when management will suffice. This appears to sometimes result in reinventing the wheel, frustration on the part of subordinates, etc. In any case, by the Bennis and Goldsmith definition, it further appears that leadership serves as the appropriate mode of direction for any given project or program, only so long as that effort lacks standards and standardized operating procedures — at which time the processes of management ought to replace the processes of leadership. Furthermore, common sense (a priori) dictates that an entity concerned with mitigating loss and maximizing gain should not stand on tradition by necessarily expecting leadership only from those in hierarchical positions, but rather, with all other things equal, that entity should enable (read: expect and require) functional experts to lead, regardless of their hierarchical positions.
Bennis, W., & Goldsmith, J. (1997). Learning to lead: A workbook on becoming a leader. Reading, MA: Addison-Wesley.
Note: I first submitted a similar statement in response to a discussion thread on Linkedin.