Think of GPO as a "one-way push"—you send a setting to a device, and you hope it stays. Windows Policy Manager, which works hand-in-hand with Mobile Device Management (MDM) solutions like Microsoft Intune, works differently. It uses Configuration Service Providers (CSPs) to maintain a persistent state on the device.
While they achieve similar goals, their architecture and "philosophy" differ significantly. Microsoft Learn Group Policy overview for Windows Server | Microsoft Learn windows policy manager
Many organizations run using Co-management in ConfigMgr (SCCM) + Intune. That way, legacy apps get GPO, while modern workloads use MDM policies. Think of GPO as a "one-way push"—you send