Those are separate server configurations. You can have multiple configurations and start them separately using "run -c myconfigname". see http://jboss.org/wiki/Wiki.jsp?page=CustomConfiguration for more details. However, these are completely separate JBoss instances.
If you are just trying separate out your various deployments, you can instruct JBoss to read from multiple directories. You can also make subdirectories in the deploy directory to logically separate your components. What you choose depends mostly on exactly what effect you are trying to achieve. If you explain your goals a bit more, maybe someone can suggest which strategy would work best.[/url]
Yes, you can specify multiple deployment directories. Lookup the jboss-service.xml in ur conf directory and look for URLDeploymentScanner at the end. There is an attribute where you can specify all ur deployment directories(comma separated list IIRC)