The Presbyterian Church is organized as a representative form of government. Members from within each congregation are elected as spiritual leaders, called elders and deacons. All members of the church have been given gifts for the building up of the body of Christ and the advancement of the kingdom of God, but the Session (the body of elders) are responsible for the general oversight and shepherding of the church.
The elders are designated as either teaching elders (the pastors of the church) and ruling elders (laity).
Deacons oversee the mercy ministry of the church as well as overseeing care for the building and finances of the church.
In addition to elders and deacons, each ministry has a ministry leader with direct oversight over that particular ministry.
You can read about Harvest Fellowship's philosophy of leadership here.