You can broadly categorize social networks, or really any communication software, based on four criteria:
- Are replies subordinate to the original post (Facebook, Instagram, blog comments) or top-level posts but linked (Twitter, Mastodon, Tumblr, blogs with pingbacks/trackbacks/webmentions)?
- Do you primarily follow people/organizations (all the above) or topics (Reddit, message boards)?
- Is the default interaction one-on-one (email, Skype) or broadcast (most of what we call “social media” these days)?
- Is it a single service (Facebook, Twitter), a collection of isolated services (message boards), or a collection of interacting services (email, the Fediverse, blogs to some extent)?
More than whether the content is likely to be short text, long text, a photo, a video, or a link, these questions define the types of connections and types of interactions that people are going to have.