Process Diagrams with ControlDraw are generally a simplified P&ID type diagram, suitable for a PCS Graphic
This is another type, in this case using typical P&ID symbols but showing something that P&ID's never do - the states of the equipment and their settings.
Most Real P&ID's are much more intricate and have many things shown on them that are not important in the context of controlling and operating the plant, for example contruction details, pipe codes, vessle nozzle sizes and so on. And they cover a larger part of the process, for example one may contain the physical equipment for one or more units and resources.
They have their place, but when it comes to a modularity they are too big. They are also too big for operating graphics - you need a huge screen for a start. And within one typical P&ID there will be several Equipment modules, Control Modules etc and little apart from notes about the functionality. One typical P&ID translates to 5 or more ControlDraw process flow type diagrams (20 may only require 50 or less).
ControlDraw also supports higher level Process Flow diagrams that are more like Process Flowsheets, they show only the major equipment items that are often on one P&ID.