Commentaries on "pastors" "elders"

 Word Biblical Commentary (p. 249-251).

[Pastors and teachers] were overlapping functions...while almost all pastors were also teachers, not all teachers were also pastors...Though the noun pomen, 'shepherd, pastor' is used of Christ himself in John 10:11, 14; Heb. 13:20; 1 Pet. 2:25, it is employed for church leaders only here in the NT. The cognate verb does, however, describe their function in Acts 20:28 and 1 Pet. 5:1-4 and Peter's activity in regard to the Church in John 21:16. It suggests the exercise of leadership through nurture, care and guidance. Significantly, the concept of the shepherd and tending the flock is often found in association with that of the bishop or overseer and overseeing (cf. Jer. 23:2; Ezek. 34:11; Zech. 11:16...; Acts 20:28, where those appointed bishops of the church at Ephesus are to shepherd the church of God; 1 Pet. 2:25; 5:2; Ignatius Rom. 9:1; Phil. 2:1, where the bishop is also called a pastor). It is probable, then, that the pastor of Eph. 4:11 fulfills the functions denoted in Paul's writings by such terms as 'to rule, manage' (1 Thess. 5:12; Rom. 12:8), 'administration' (1 Cor. 12:28) and episkopos, 'bishop, overseer' (Phil. 1:1)...Because the general notion of overseeing had close associations with the shepherd in Jewish thought, it is understandable that the term 'pastor' could become interchangeable with 'bishop' in the Christian movement. It is the equivalent to presbyteros, 'elder' of Acts 14:23; 20:17; 1 Tim. 4:14; 5:17, 19; Titus 1:5; 1 Pet. 5:1, 5; James 5:14." 

International Critical Commentary, Eph 4.11

This much is clear, that pastors and teachers differ from the preceding classes in being attached to particular Churches. The name "pastors" implies this, and this term no doubt includes episkopoi and presbuteroi. Compare 1 Peter 5.2 (addressing the presbuteroi; 1Pet 2.25; Acts 20.28). The "pastor" of a Christian Church would, of course, be a teacher as well as a governor; it was his business to guide the sheep of the flock; cf. 1Tim. 3. 2; also Tit. 1. 9. But there would naturally be other teachers not invested with the same authority and not forming a distinct class, much less co-ordinate with the episkopoi.

TDNT, vol. 6, p 498.

"Only once in the NT are congregational leaders called shepherds, namely in the list of offices in Eph. 4:11...These shepherds are the leaders of the local church (elders in 1 Pet. 5:1; Acts 20:17; bishops in Acts 20:28)."