Charles Ellicott Commentary Acts 20:17

"And from Miletus he sent to Ephesus, and called to him the elders of the church." — Acts 20:17 (ASV)

And from Miletus he sent to Ephesus, and called the elders of the church.—We find from Acts 20:28 that they were also known as episcopi (“bishops,” or “overseers”), the two names being interchangeable at this period. The Apostle stood in relation to those who bore these titles as a later Bishop did to the elders under him. (See Notes on Philippians 1:1; Titus 1:5–6; 1 Peter 5:1–2.)

The many presbyters probably each represented a distinct church or congregation. Most, if not all, of these must have been ordained by the Apostle himself. He had found them loyal, faithful, and singularly receptive to the truth (Acts 20:20; Ephesians 3:4). He was passing, as he thought, to far-off regions, never to revisit them, and he was naturally anxious to give them parting words of counsel and warning.