The Liberty Profile based ELM server would be the server that your company runs to allow software development. This server contains an EWM Project area that hosts the code for the example extension of the Rational Team Concert Extensions Workshop. You can run this server in debug mode and connect to it using the remote debug connection. Usually you would not do this. You would have to deploy your extension on it to see it running. This is only the last step of developing.

The Jetty server runs a server in your development environment. The features, including your custom extension you develop, can be specified in the launch you use. The bundles and features specified are automatically deployed on Jetty. You can fully debug your extension including hot code replacement, if you fix issues. This is sometimes not working and the server will tell you.

You develop your stuff using the Jetty debug server, you version your code in the Liberty development server. You use the Liberty development server to test the final deployment - before you try that on your production server.