Azure Monitor Agent (AMA), collects monitoring data from VMs and sends it to Azure Monitor

For non-Azure VMs to be integrated with Sentinel they need to be have the Azure Arc agent installed, which makes them Arc-enabled.

Azure Arc agent is also called the Azure Connected Machine agent.

https://www.infusedinnovations.com/blog/intelligent-cloud/step-by-step-guide-to-deploy-azure-sentinel

https://techcommunity.microsoft.com/t5/azure-sentinel/azure-sentinel-agent-collecting-from-servers-and-workstations-on/ba-p/811760