parent & module

Project Inheritance (parent)

Elements in the POM that are merged are the following:

dependencies
developers and contributors
plugin lists (including reports)
plugin executions with matching ids
plugin configuration
resources

Project Aggregation (module)

But instead of specifying the parent POM from the module, it specifies the modules from the parent POM. By doing so, the parent project now knows its modules, and if a Maven command is invoked against the parent project, that Maven command will then be executed to the parent's modules as well. To do Project Aggregation, you must do the following:

Change the parent POMs packaging to the value "pom".
Specify in the parent POM the directories of its modules (children POMs).

如何选择

If you have several Maven projects, and they all have similar configurations, you can refactor your projects by pulling out those similar configurations and making a parent project. Thus, all you have to do is to let your Maven projects inherit that parent project, and those configurations would then be applied to all of them.