Depending on your subscription, and status of your designer, you have access to the following environments to publish to:
Only available for commercial subscriptions. This is the environment that people see when they go to the URL of your application. Choose to publish here if your design is done, and you tried it in the Lab.
Available to all subscriptions. Choose this environment if you want to test your application, or your latest idea.
The Triggre Discovery is where you discover how to design applications with Triggre, hence the name. You can only publish here if you are doing a learning exercise.