You can deploy applications or individual modules that are independent of applications. The runtime and file system implications of application-based or individual module-based deployment are described in Runtime Environments.
Individual module-based deployment is preferable when components need to be accessed by:
Other modules
J2EE Applications
ACC clients (Module-based deployment allows shared access to a bean from an ACC client, a servlet, or an EJB component.)
Modules can be combined into an EAR file and then deployed as a single module. This is similar to deploying the modules of the EAR independently.