Modern document libraries combine the power of SharePoint with OneDrive usability
Modern document libraries have an updated user interface that offers an experience similar to OneDrive, so it’s more intuitive to create a new folder and upload files in the browser. The ribbon has been replaced with a trim command bar, which provides intelligent commands relevant to the tasks at hand. If your organization has customized the ribbon with buttons that map to critical business functionality in your enterprise, those buttons will appear in the command bar as well. With this update, each new Office 365 group now gets a full modern document library, replacing the former “Files” page.