Managers vs. Leaders
To add to your post, leaders should strive for inclusion. According to Graen and Uhl-Bien (1995), Leader-Member Exchange Theory (there is a great discussion on this theory in this week's chapter) says there are basically two types of relationships between leader and follower. The first type is formal and structured defined by roles, job descriptions, etc. According to the theory, people in this first category are in the out-group. The second type of relationship is less formal where the leader and follower communicate freely, negotiate responsibilities, and might even socialize, go to lunch together, etc. People in this category are in the in-group. In either situation, the leader and the follower have a one-to-one individual relationship (vertical dyad) with its own characteristics. So, a leader may be structured toward one employee and sociable with another.
Do you think employee productivity is affected based on the leader's behavior and the relationship with people in the in vs. out -group?
Graen, G. G., & Uhl-Bien, M. (1995). Relationship-based approach to leadership: Development of leader-member exchange (LMX) theory of leadership over 25 years: Applying a multi-level multi-domain perspective. Leadership Quarterly, 6(2), 219-247.