While PluGeth has been designed to be versatile and customizable, when learning the project it can be helpful to think of plugins as being of four different archetypes.
A subcommand redifines the total behavior of Geth and could stand on its own. In contrast with the other plugin types which, in general, are meant to capture and manipulate information, a subcommand is meant to change to overall behavior of Geth. It may do this in order to capture information but the primary fuctionality is a modulation of geth behaviour.
..NOTE:: Plugins are not limited to a singular functionality and can be customized to operate as hybrids of the above. See `blockupdates`_ as an example.