I came across a video tutorial, where the tutor described the term or meaning of group to be that of a forum.
That's not entirely accurate.
Earlier on in the year I had a closer examination to this inaccurate paradigm. A client presented me with a prototype produced by their contracted development agency. They described there situation as confused and dismayed, by:
A. the lack of collaboration - clients objectives not be realized through close analysis, lack of communicative research.
B. the result
Within several days I presented myGroups prototype In using Drupal Groups with additional interactive wireframes presenting extra functionality needed to be developed in a Drupal custom module.
This is my standard practice, researching yourself, working on the IA and the UX, establishing connections between the client and the development and production, and recognizing the full scope of the solution.
Forums as a set of posts that can be categorized using vocabulary, taxonomy. A set of posts, comments and discussion threads. You can add extra functionality and create files sharing as well.
We are all familiar with Facebook groups.
Drupal has its own community built versions, perhaps leading the way for Facebook with Organic groups, however my choice is Drupal Groups. There's an excellent article https://www.deeson.co.uk/labs/group-alternative-organic-groups .
Groups downloaded of Drupal.org https://www.drupal.org/project/group
Organic groups or OG makes a content type a group, and dependent on entity reference to link, groups, terms and nodes together, however Group creates groups as entities so you can be more flexible, allowing multiple roles and permissions connected with it, and also the ability to create sub-groups.