- Leadership is setting a new direction or vision for a group that they follow, ie: a leader is the spearhead for that new direction
- Management controls or directs people/resources in a group according to principles or values that have already been established.
Leadership without management
...sets a direction or vision that others follow, without considering too much how the new direction is going to be achieved. Other people then have to work hard in the trail that is left behind, picking up the pieces and making it work. Eg: in Lord of the Rings, at the council of Elrond, Frodo Baggins rescues the council from conflict by taking responsibility for the quest of destroying the ring - but most of the management of the group comes from others.
Management without leadership
...controls resources to maintain the status quo or ensure things happen according to already-established plans. Eg: a referee manages a sports game, but does not usually provide "leadership" because there is no new change, no new direction - the referee is controlling resources to ensure that the laws of the game are followed and status quo is maintained.
Leadership combined with management
...does both - it both sets a new direction and manages the resources to achieve it. Eg: a newly elected president or prime minister.