“Conversion, though it may seem, in some respects, to fall in with regeneration and the effectual calling, yet may be distinguished from them both. Regeneration is the sole act of God; conversion consists both of God’s act upon men, in turning them, and of acts done by men under the influence of converting grace; they turn, being turned. Regeneration is the motion of God towards and upon the heart of a sinner; conversion is the motion of a sinner towards God, as one (Charnock) expresses it. In regeneration men are wholly passive, as they also are in the first moment of conversion; but by it become active: it is therefore sometimes expressed passively; ‘you are returned,’ or converted (1 Peter 2:25), and sometimes actively; ‘a great number believed and turned to the Lord’ (Acts 11:21)…. The effectual calling is the call of men out of darkness to light; and conversion answers to that call, and is the actual ‘turning’ of men from the one to the other; so that, with propriety, conversion may be considered as distinct from regeneration and the effectual calling.” ~
John Gill, A Body of Doctrinal Divinity, Book 6, Chapter 13.