The S is a trim level
There's a few different ones like the "equation", "profile" and "S", and as far as I know they all had different things as standard. Some had Aircon, some had power steering, some had different coloured seats, that sort of thing
As far as actual K11 micras, there is the 1992-1997 which is pre-facelift K11, the 1998-2001 which was K11 facelift, and the 2001-2003 which was facelift K11C (also called "second-facelift")