IC has different pinouts on different packages?
"does not mention anything" except this:


  Segment Driver Outputs
  
  The LCD drive section includes 20 segment outputs SEG0 ~ SEG19 or 16 segment outputs SEG4 ~ SEG19 which
  should be connected directly to the LCD panel. The segment output signals are generated in accordance with the
  multiplexed column signals and with the data resident in the display latch. The unused segment outputs should be
  left open-circuit when less than 20 or 16 segment outputs are required.
  
  Column Driver Outputs
  
  The LCD drive section includes 4 column outputs COM0~COM3 or 8 column outputs COM0~COM7 which
  should be connected directly to the LCD panel. The column output signals are generated in accordance with
  the selected LCD drive mode. The unused column outputs should be left open-circuit if less than 4 or 8 column
  outputs are required.