There are two ways to install the .NET microservices agent into Azure App Service:

Azure Site Extension is used by Ops teams that may not have access to source files, or would not like to modify or recompile them, yet still want to monitor their Azure projects and solutions.

The NuGet Package is used by Dev teams to deploy the .NET agent so they can include the agent binaries, scripts, and configurations in their project and configure it using Visual Studio or other IDE.