1: χιλίαρχος
(Strong's #5506 — Noun Masculine — chiliarchos — khil-ee'-ar-khos )

denoting "a commander of 1000 soldiers" (from chilios, "a thousand," and archo, "to rule"), was the Greek word for the Persian vizier, and for the Roman military tribune, the commander of a Roman cohort, e.g., John 18:12; Acts 21:31-33,37 . One such commander was constantly in charge of the Roman garrison in Jerusalem. The word became used also for any military commander, e.g., a "captain" or "chief captain," Mark 6:21; Revelation 6:15; 19:18 .

2: στρατηγός
(Strong's #4755 — Noun Masculine — strategos — strat-ay-gos' )

originally the commander of an army (from stratos, "an army," and ago, "to lead"), came to denote "a civil commander, a governor" (Latin, duumvir), the highest magistrate, or any civil officer in chief command, Acts 16:20,22,35,36,38; also the "chief captain" of the Temple, himself a Levite, having command of the Levites who kept guard in and around the Temple, Luke 22:4,52; Acts 4:1; 5:24,26 . Cp. Jeremiah 20:1 .

3: ἀρχηγός
(Strong's #747 — Adjective — archegos — ar-khay-gos' )

see AUTHOR (No. 2).

Acts 28:16