Ok, there are four modules so far. Core, which is the base. It consists of APIs and a few visual enhancements. Then you have Science&Industry, which requires core. It adds machines and automation, and was inspired by the technic pack and FTB. That kind of thing. Then there is Rails&Transportation, which is the smallest module. It requires Science&Industry and core. It contains methods of movement, using advanced rail and cart systems, as well as a few other ideas that are yet to be implemented. Lastly, there is Fantasy&Adventure, which adds opportunities for exploration, as well as magic. It is mainly inspired by the now deprecated yogbox, and requires core. I liked using both, and often wished that there was some overlap. However, the reason why I have divided it up is because some people I know do not like the automation, while others do not like the magic and exploration. Also, having all of the modules can be a bit stressful for some peoples computers.