There is no difference. Opening and closing the bail does not produce line twist at all, regardless of how it is done.
Line twist on a spinning reel results when the bail is turned, but no line retrieved, such as when a person keeps reeling without retrieving any line while playing a fish.
It is also generated when line is loaded on a reel incorrectly.
I agree that closing the bail manually or by turning the handle, in and of itself, does not make any difference in line twist. With that being said, I believe closing the bail manually inevitably results in less line twist because of what usually occurs directly thereafter.
After a cast, there will always be some slack line, and maybe even a twisted loop, hanging not far from the spool of a spinning reel. If the bail is closed by turning the handle, this bit of slack line or twisted loop will be wound onto the spool. If you lift the rod or otherwise try to remove the slack with the bail open while also turning the handle, the line will not be tight, and so the slack will not be taken up.
On the other hand, I've developed a habit of always closing the bail manually before turning the reel handle. With the bail closed, I then either lift the rod until the slack or loop is taken up or stretch the line out with my support hand if necessary. Because the bail is closed, I can tighten up the line before beginning to wind. Over the course of a day, I believe this technique results in less line twist.
Slack line is your enemy.