There are some differences between VSO and the on premises edition of
TFS. For example, CodeLens support, customizing TFS, (e.g. adding your
own fields or states to the Bug work item type), integration with SQL
Server Reporting Services (SSRS) and SharePoint to create team project
dashboards that show rich reports generated by SSRS are only available
in the on premises edition of TFS. However, Application Insights and
automatic upgrades to the latest version of TFS are only available on
VSO.