Difference between these two lists?

[Chris Angelico]

On Tue, Jan 8, 2013 at 12:06 PM,  <andydtaylor at gmail.com> wrote:
> I think I can answer my own question on reflection.... the first one is actually  a string I think? I was confused by the square brackets around the placeholder %s.

That's correct. Your first line is putting square brackets around a
comma-joined list of strings; the second gives the representation of a
list. They happen to be superficially similar.

ChrisA