Leaders influence. Managers direct. While it may not be that black and white, leaders generally do focus on what matters and why as managers focus on how. Both use different forms of influence and direction at different times, but leaders have a bias to influencing by inspiring and enabling through advice and counsel while managers have a bias to command and control.
LEADER: Influence, brilliant but sometimes lonely, tend to be active, develop new approaches, maintain inner perceptiveness, not satisfied with status quo.
MANAGERS: Direct, emphasize rationality and control, adopt impersonal attitudes, view work as an enabling process, prefer working with others, maintain with existing balance of social relations.