There's a comparison matrix documenting the major features available in each ArcGIS Enterprise version as well as what's currently available Online and a "what's new" topic that provides more detail. These don't document every minor enhancement but do cover the big ticket differences.
The copy section link feature is not available in any currently released version of ArcGIS Enterprise, and it will not be available in v11.0 when that is released next month . Unfortunately, there is a technical limitation that's blocking bringing it to Enterprise. We are going to look at it again soon, however, to see if there's a way we can bring it to Enterprise 11.1.
(EDIT, 7/1/22: Updated to correct, external hyperlinks)
Owen Evans
Lead Product Engineer | StoryMaps