Style versus Leadership
My first thought is that it might be a matter of position. I think individuals could have a certain STYLE whether they hold a position of authority or not
LEADERSHIP suggests the style is displayed in a position of authority
This response, however, fails to deal with the reality that many people who do not hold a 'position' of authority are nonetheless leaders by virtue of their style. When you look at the attributes listed for servant leadership you realize they can be displayed by anyone regardless of role in the organization.