There are three terms used in the Greek New Testament to describe the roles of church leadership. We can't understand one without also understanding the other two, since they all work together to provide leadership over Christ's sheep. What's the difference between a pastor, an elder, an overseer, and a deacon?
Episkopos
This word episkopos (from which we get Episcopal) is used a total of 5 times in the New Testament, always in reference to someone who has authority to lead in ministry. It is usually translated "overseer" or "bishop." Clearly, it is a position of leadership, most commonly thought to refer to the position of pastor. The difficulty in understanding the full meaning of this word comes when we try to compare it to the second word used in scripture for leadership: presbuteros.
Presbuteros
The word presbuteros occurs 72 times in the New Testament, and it has a range of meanings. The majority of the time (57 times) it is translated "elder" and means a position of leadership in the church, like a pastor or other member of church leadership. Importantly, it differs from episkopos in that it also assumes the quality of old age. In other words, elders are leaders, in part, due to the wisdom and spiritual maturity they have obtained through a life-long walk with Christ. In fact, the word presbuteros is also translated at times to mean "older man" (10 times) and even once as "older woman" (1Tim 5:2).
But there is yet still another term for leadership in the Bible we must consider: diakonos.
Diakonos
The word diakonos means “one who serves in ministry” or more generally, "servant." The word appears 29 times in the New Testament. Of those 29 times, it is translated (by the NASB) as "deacon" three times, as "minister" seven times, and as "servant" 19 times. Consequently, the best definition of the duties of a diakonos is one who ministers to the church through their service.
Considering how Paul uses the term in Phil 1:1 and in 1Tim 3, it's fair to say that he viewed diakonos as playing a leadership role in the church, albeit a lessor role compared to epsikopos or presbuteros. For example, Paul expected that the determination of who may serve as diakonos would fall to the other leaders in the church (1Tim 3:10), clearly suggesting that diakonos answer to the other two positions.
Nevertheless, diakonos are part of the leadership within a church, and they express their leadership primarily through acts of service for the benefit of the entire congregation (including other leaders). The best example of the appointment of diakonos within the church is found in Acts 6 where Stephen and six other men are appointed to positions of service by the primary leaders in that church.
Notice that several of these men eventually became evangelists themselves (e.g., Stephen, Philip), demonstrating that those who begin ministry in positions of service as diakonos are not precluded from eventually taking other roles in leadership. To summarize then, diakonos are lessor leaders focused on service, while episkopos and prebuteros are primarily pastoral leaders over a congregation.
Still, several questions remain: what is the difference between episkopos and presbuteros, especially in regard to their roles, and what is their relationship to the diakonos? There are three places in scripture we need to consult for the answers to these questions.
The first passage is Acts 20:17–28. In that passage, the Apostle Paul is nearing the end of his ministry, when he gives a final word of exhortation to the church in Ephesus. He begins in verse 17 by addressing the presbuteros (elders) of the church, yet a few verses later in the passage, Paul refers to these same men in verse 28 as episkopos, or overseers. By describing the same group one time as presbuteros and a second time as episkopos, Paul seems to consider the two words to be synonyms for church leaders.
The second passage of scripture to consider is Titus 1. In verse 5, Paul reminds TItus that he left him in Crete with instructions to appoint presbuteros (i.e., elders) over every city. In this context, an elder is clearly a position of leadership over a church, yet just a few verses later Paul begins to describes the qualifications for an elder using the word episkopos (i.e., overseer) to describe this same group. Once again, Paul seems to use these two words for leader interchangeably.
It seems fair to conclude from these two passages that scripture makes no clear distinction between a prebuteros (elder) and an episkopos (overseer) in terms of their role in leadership. Therefore, we should consider these two terms to refer generally to leaders over a church, whether they serve as a pastor, an elder or both.
This fact also suggests that Paul was not especially concerned over the particular organizational form that church leadership assumed, though he does make clear he expects a plurality of leadership (i.e., overseers, elders) rather than just a single leader.
Before we conclude this examination, we need to consider one final passage in 1Tim 3. In this chapter, Paul begins in verse 1 by stating the qualifications for an episkopos (i.e., overseer). Later in the chapter, Paul switches to describing the qualifications for a man to serve as a diakonos (1Tim 3:8). By these verses, we learn an important additional piece of information. We can see that Paul envisions a clear break in leadership between overseers/elders on the one hand and deacons on the other hand. While both groups are considered leaders in the church, the first group (e.g., overseers/elders) appoints and rules over the second group (deacons).
In conclusion, a classic New Testament church ought to be led by a plurality of overseers, including older, more mature elders who guard the flock, together with a cadre of secondary leadership called deacons focused on serving the body. Though churches often depart from this ideal form, that certainly doesn't preclude God from working through those churches nonetheless, as every church has its flaws and God accomplishes His work through us in spite of our form, not because of it.
