What's the difference of Vs from Vs0 or Vs1?
Vs is the generic term.  However, since stall speed varies depending upon how the aircraft is configured (in particular the flaps), we break that down into Vs0 for landing config and Vs1 for cruise config.  In theory, we should list the stall speed for every possible configuration, but it's generally sufficient to list just those two because all others should be somewhere in between.