People who work in the strategy field are responsible for designing and executing market and company strategy. Skills and techniques used within strategy are business analysis, data analysis, opportunity mapping and strategic planning.
In a leadership position someone is responsible for a group of people, typically an organizational unit or the entire organization, depending on the size of the organization. Leaders are responsible and accountable for overseeing and guiding strategic activities, programs and managers who report to them. Just a few people in an organization are typically in a leadership role.