An Advantage Tool is the term used for managing "Structured Content". This is content that follows a known pattern with expected behaviours (i.e. news articles, calendar events, people profiles, etc.)
A tool is used to manage the data, and a module is used to express the content on the front end. Often a module will utilize the "AdvantageModuleRewrite" inheritance so that Friendly URLs are available.
The Front-end expression AdvantageModule and AdvantageModuleRewrite utilize the AdvantageModuleEngine (this.ModuleEngine) in order to access the data stored.