The Office Fabric-UI is the offical front-end framework for building experiences in SharePoint and Office 365. To handle the various development frameworks, the Fabric Core is the base library which is extended to:
The Office Fabric-UI React framework provides the components used in the O365 user experience. Unfortunately, the components still need to be connected to SharePoint. The gd-sprest-react library extends the Office Fabric-UI React framework to include components like the People Picker or List Form.