So, then, what about Apostles, Prophets, Evangelists, Pastors, and Teachers?
These are callings of grace, roles and functions within the Body of Christ, for its edification, to help every member fulfill each individual calling to and toward the Lord's Church, equipping every saint for the work of the ministry so that the local congregation can measure up to the fullness of the standard of Christ.
Ephesians 4 makes it pretty clear.
As it pertains to Bishops, Elders, and Deacons, these are facilitators who help organize and administrate the various needs of the Body, up to and including how meetings are to progress and if any points of order are to be addressed. But also, they serve to help with financial needs in the church, they visit the sick and elderly and disabled, act as liaisons to the community at large, are points of connection between churches, and work to establish the local congregation as a functioning body which upholds the standards of the Holy Scriptures so as to represent Christ properly in the world.
As such, they are examples who are called to stand out and show the rest of the congregation what a Godly life is to look like, so others can emulate them. They pattern themselves after Christ, and relay that pattern to everyone else who desires to live the life Christ would have them live.