Basically, with Volts/Enigma you get another sequence clocked to the same tempo, based on the input from the main module and how the pots are set. With Pulses/Morcom you get a number of parallel semi-random pulse sequences related, assumingly, to whatever gets fed to Rungler. It’s probably easier to figure out what they do just by trying it out. With Turing Machine they were a lot of fun in a small space, I’d assume with Benjolin as well.
(You asked about the passive vs. powered earlier - in case AfterLater didn’t reply yet, they do require a small amount of power… but at least in the case Turing Machine, that power gets fed from the main module and not directly from the power bus. So all you need is a connecting cable to the main module. I assume it’s the same with the Benjolin.)