I added information on the REDCap-ETL application. My modifications consider an application to be a program or script that you would download to your system and run. It is something that can be run on its own, so external modules would not be included here, since they are extensions to REDCap that have to be run within REDCap, and libraries would not be included here, since they are called by an application that is run. In this context, I would consider the external module repo to be a website and not an application.
I added information on the REDCap-ETL application. My modifications consider an application to be a program or script that you would download to your system and run. It is something that can be run on its own, so external modules would not be included here, since they are extensions to REDCap that have to be run within REDCap, and libraries would not be included here, since they are called by an application that is run. In this context, I would consider the external module repo to be a website and not an application.