The difference between "priest," "minister," and "pastor"
A priest is simply anyone who intercedes with God for another. A minister is simply a servant. But a pastor is a shepherd. The pastoral ministry is a vocation. It is something to which a someone is specifically called. A layperson (as Article XIV of the Augsburg Confession points out) has no more business preaching or administering the Sacraments than a pastor does doing brain surgery, representing a person accused of committing a crime in court, or having a baby (NOTE: women are specifically forbidden the pastoral office by Scripture).