Generally you'll want to use pysight.main.run as the standard\default way to run this application. It can be run without any arguments, which will open the GUI <gui>, or run with a pre-existing configuration file name.
The other two functions allow you to run PySight on several list files one after the other, either in a sequential manner (pysight.main.run_batch_lst) or in a parallel manner (pysight.main.mp_batch).
pysight.main.run
pysight.main.run_batch_lst
pysight.main.mp_batch