There are extensive differences between these versions. SCCM 2012 is the predecessor to Endpoint Configuration Manager (ECM), the basic framework and look of the two products are still the same. However, ECM has been upgraded every four months for many years. ECM includes a new service connection point site system role which enables many cloud-based features and uploads diagnostics and usage data to Microsoft Azure. In addition, many improvements have been made to client deployment, operating system deployment, application management, software updates, compliance, and mobile device management, as well as regularly adding new features and capabilities!