I am going to start seriously advocating Hubzilla for CONfederated communities. Apart from having it installed (soon to be, as soon as I get to understand Docker), I would be happy to see some structured (perhaps as an infographics) view of various terms and features.
I can intuitively group them:
instance, account
Identity, channel, privacy group, forum
tag, category
post, article

But it will need time and practice to get relationships between them. So, perhaps someone did the job before?
  
I know that  you can find infos in the help-pages... this can help a little.