Managers deal more with making sure that the organization operates effectively in terms of its stated goals or objectives; leaders deal more with plotting the future of the organization, including making changes in its stated goals and objectives. Leaders "set the tone" for the organization; managers make sure that the leader's goals are carriede out. Leaders ideally inspire; managers need not be as inspirational.
At the higher levels of management, managers are not looking at the little details of what goes on on a day-to-day basis in their firms (assuming that we are talking about large companies). Instead, they have to focus more on things like long-term strategies that are more conceptual than technical.