I dont know what is run-time deployment descriptor. J2EE deployment descriptor is assocaiated with J2EE application and configures the deployment component. For example application.xml is assocaiated with ear application.
There are two types of deployment descriptors: J2EE and runtime.
A J2EE deployment descriptor is defined by a J2EE specification and can be used to configure deployment settings on any J2EE-compliant implementation.
A runtime deployment descriptor is used to configure J2EE implementation-specific parameters. For example, the Sun Java System Application Server Platform Edition 8 runtime deployment descriptor contains information such as the context root of a Web application, the mapping of portable names of an application's resources to the server's resources, and Application Server implementation-specific parameters, such as caching directives.
The Application Server runtime deployment descriptors are named sun-moduleType.xml and are located in the same directory as the J2EE deployment descriptor.