The news article details page for each article, and the event details page for each event, both have the social sharing buttons automatically placed at the top so people can easily share the news or event to their own Facebook, LinkedIn, Google+, and/or Twitter accounts.
In addition to that, every page on the site has a "share" link located in the right-hand side of the "breadcrumb bar" (the line below the main menu) which has even more sharing options available, and again is on every single page of the site including the news / events pages (so there's two sharing options on those pages).
The social networking options within the control panel are provided to link and/or embed content from the organization's Facebook page / Twitter account / Instagram account. That's different than the above in that it's another way for the organization to broadcast information out to their "followers" (membership). But the general public can't publish anything to those accounts because they don't own them - these links are provided so that they can follow those accounts.
Hope that helps,