Admin Modules are a series of modules that the Admininstrator of a website can place on Pages via Site Builder. For the most part, each page can hold multiple copies of these modules. They allow the Administrator to customize the website to fit their needs.
Some Admin Modules can be made into Modules that are stored under the Custom Modules tab within Site Builder. These custom modules can then be reused without needing to update configuration options on multiple pages. These modules are marked below with an *.