I've been wondering on this one for some time now, but still can't quite figure it. For all the similarities that one can see between "preaching" and "teaching" (and besides things like audience involvement), what is the real difference between the two? Focus? Delivery? Approach? I'm always thankful to God for your help.
"And He Himself gave some to be apostles, some prophets, some evangelists, and some pastors and teachers, for the equipping of the saints for the work of ministry, for the edifying of the body of Christ" (Ephesians 4:11-12).
There are three words which describe the same job within the church: evangelist, preacher, and minister. The work of an evangelist is distinct from a teacher as it is listed separately in Ephesians 4:11-12. Yet there is overlap in the duties because in this same verse the apostles, prophets, evangelists, pastors and teachers are all charged with equipping and edifying the saints.
The word "evangelist" is translated from a Greek word which refers to a person who brings joyous news of victory from the battlefront. When the same word is used in reference to what that person does, it is often translated "preaching the gospel" as in Romans 1:15. An evangelist, then, is a person who brings good news to the world.
The same work is also called "preaching." Paul said he was eager to preach the gospel (evangelize) in Rome in Romans 1:15. In II Corinthians 1:19, Paul said that he, Silvanus, and Timothy had preached in Corinth. In I Timothy 2:7, Paul said he was appointed to be both an apostle and a preacher. The word translated "preacher" comes from the Greek word for a herald or a town-crier. Such a person delivered the messages and commands of the king. He was not the originator of the message, but merely its deliverer.
Yet another word for the same work is ministry. "But I have written very boldly to you on some points so as to remind you again, because of the grace that was given me from God, to be a minister of Christ Jesus to the Gentiles, ministering as a priest the gospel of God, so that my offering of the Gentiles may become acceptable, sanctified by the Holy Spirit." (Romans 15:15-16). "To be specific, that the Gentiles are fellow heirs and fellow members of the body, and fellow partakers of the promise in Christ Jesus through the gospel, of which I was made a minister, according to the gift of God's grace which was given to me according to the working of His power." (Ephesians 3:6-7). This word comes from the Greek word for a servant. The same word can refer to a servant in a household, a deacon in the church, or a minister. It is the context which defines which English word should be used. A minister serves Christ and His church by teaching the word of God.
The terms are used interchangeably. "Of this church I was made a minister according to the stewardship from God bestowed on me for your benefit, so that I might fully carry out the preaching of the word of God" (Colossians 1:25). Paul was made a minister in order to preach the word of God. "But you, be sober in all things, endure hardship, do the work of an evangelist, fulfill your ministry." (II Timothy 4:5). Timothy's ministry was to do the work of an evangelist.
The term "teacher" refers to an instructor. A teacher's job is to give greater understanding of God's Word. Generally, a teacher is instructing a willing audience -- people seeking to know more about God and His Laws. A preacher must deal with both willing and hostile audiences. There will always be people uninterested in the gospel. A preacher's duties also go beyond just instruction in the word of God. See "Preachers" for more details.
Therefore a preacher's duties include teaching, but a teacher isn't a preacher.