People who work in the marketing field are responsible for building brand and acquiring marketing leads. Skills and techniques within marketing are lead acquisition, conversion, retention, content creation, brand management and PR.
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.