In his book Preaching with Purpose: the Urgent Task of Homiletics, Jay Adams makes a distinction between the lecturer and the preacher, which I am very familiar with in a practical sense. I do both. Some of my Sunday messages are lectures and some are sermons. While it is my aim to always preach a sermon, there are times according to the providence of God that a lecture-format is more appropriate.
Here is Adams clarifying the distinction:
“The preacher does a good job of considering the historical-grammatical exegesis of the preaching passage, considers it theologically and rhetorically, and then – simply tells his congregation what it means. His response, and consequently theirs as well, is to say, ‘Well, not I understand it,’ and that’s that! That is not preaching. True preaching does all of the above, but it also identifies the telos (purpose) of the passage, build the message around it, and calls on the congregation for a response that is appropriate to it. It works for change.
“Preaching that stops short of asking for change that is appropriate to the Holy Spirit’s letters to His church is not preaching at all; at best, it is lecturing.
“The lecturer speaks about the Bible; the pastoral preacher speaks from the Bible about the congregation. He tells them, what God wants from them. These are two distinct stances. …
“Everything that the lecturer says may be quite true, but if that truth doesn’t come to grips with the congregation in such a way that it can change their lives in accordance with the purpose of the Holy Spirit, it may be lecturing, but it isn’t preaching.” (pgs. 44-45)
A lecture usually reminds the audience of what God has done in the past; a sermon usually reminds the audience of what God is doing in the present. A lecture usually uses 3rd person pronouns (e.g., “he,” “she,” “they”); a sermon usually uses 2nd person pronouns (e.g., “you”).
Either way, both sermons and lecture have their place in the local church. The sermon, as Adams describes it, ought to be more prevalent – like for the main worship service. The lecture is usually better suites for smaller audiences – like a Sunday School class.
“Preach the word; be ready in season and out of season; reprove, rebuke, and exhort, with complete patience and teaching” (II Tim 4:2).