It seems Calgal is discussing the OPC... I don't know how that varies from the PCA, do let's look there...
PCA- we have three main types of officers
Teaching Elders- Senior, Associate, and Assistant Pastor
Ruling Elder- Elected by the congregation, examined by the existing Session.
Deacons- Same method of selection as RE's
BCO 7-2 said:
The ordinary and perpetual classes of office in the Church are elders and deacons. Within the class of elder are the two orders of teaching elders and ruling elders. The elders jointly have the government and spiritual oversight of the Church, including teaching. Only those elders who are specially gifted, called and trained by God to preach may serve as teaching elders. The office of deacon is not one of rule, but rather of service both to the physical and spiritual needs of the people. In accord with Scripture, these offices are open to men only.
It is also interesting to note, that above the local church, there is no allowed distinction between RE and TE
BCO 8-9 said:
Elders being of one class of office, ruling elders possess the same authority and eligibility to office in the courts of the Church as teaching elders. They should, moreover, cultivate zealously their own aptness to teach the Bible and should improve every opportunity of doing so.
A Brief distinction- Associate Pastors are members of the Session (As TE's). Assistant Pastors are NOT members of the session. (BCO 12-1)
Now, how are the Elders and Deacons selected?
Senior Pastors MUST be elected by the congregation They are ordained by the presbytery, but must be first hired by a vote of the congregation. This prevents the congregation from having a SP that they do not want there- which can happen in the RCC or UMC models.
Now on to Associate and Assistant Pastors- and why we use both terms...
BCO 22-2 said:
The pastor and associate pastor are elected by the congregation using the form of call in BCO 20-6. Being elected by the congregation, they become members of the Session.
BCO 22-3 said:
An assistant pastor is called by the Session, by the permission and approval of Presbytery, under the provisions of BCO 20-1 and 13-2, with Presbytery membership being governed by the same provisions that apply to pastors. He is not a member of the Session, but may be appointed on special occasions to moderate the Session under the provisions of BCO 12-4.
BCO 22-4 said:
The relationship of the associate pastor to the church is determined by the congregation. The relationship of the assistant pastor to the church is determined by the Session. The dissolution of the relationship of both is governed by the provision of BCO 23.
That pretty much speaks for itself. Now, BCO 23-1 requires that for a Pastor, whatever the classification, to be removed from duty- he must be released by what body called him- SP's and Associates by the congregation, and Assistant's by the Session.
Enough about Pastors- let's take a brief look at RE's and Deacons. BCO 24 is very long- but the basic idea is that both must be elected by a vote of the congregation.
ABove this level- There is the Presbytery and General Assembly- but I don't have the experience there to discuss them. I'll leave them for someone else.