Jesus said very clearly in Matthew 28:18 that "All authority in heaven and earth has been given to me." Jesus is the head of the church; everyone else falls under his Lordship and direction. God also gave a picture of what leadership in the local church should look like. The example of the early church was that elders were appointed to serve as the leaders of the local congregations.
At Cross Plains, we strive to model our structure based on the instruction from the Bible. Because of this we view elders (with an emphasis on the plural nature of this word) as the earthly leaders of the local church. Elders are encouragers, equippers, and examples, not enforcers. They are care-givers and counselors, not care-takers and controllers. The description that God gives for elders is not about position or power; it stresses accountabilty and responsibility. Depending on the translation or passage you read, there a few other terms that the Bible uses interchangeably with the word elder. Some examples are fellow-elder, care-giver, overseer, and pastor. Each of these terms refers to the same thing: a group of individuals in a congregation who have ultimate accountability for the welfare of the congregation as a whole as well as its individual members.
The word "deacon" very plainly means servant. Deacons are servant-leaders. Deacons are not co-elders. The main function of deacons is to serve the local church body under the direction & leadership of the elders. The qualifications for deacons are found in 1 Timothy 3:8-12.