The Development environment is a dedicated environment where the product or feature is designed and tested. For more information, see Developing and Testing.
The Quality Assurance (QA) environment allows you to validate the development processes created in the development environment without shutting down development work. Once the processes are validated, they are propagated to the Production environment.
In this environment, the Git Repository is no longer required and the Talend CommandLine application is optional as the artifact sources have already been generated.
The Production environment is a live environment where your product or feature is deployed into production.
In this environment, the Talend CommandLine application as well as the Git/Subversion server are no longer required.
For more information, see Deploying to QA and Production environments.
To understand how these three environments are linked together, see Implementation with Talend.