Microblogging is tweeting, or tooting, or similar. Very short (micro) one-way messaging (blogging). The term “blog” is an abbreviation of “web log”, which is simply a series of someone’s thoughts posted on the internet for whomever happens to pay attention. Readers are mostly passive.

https://en.wikipedia.org/wiki/Microblogging

A thread is a collection of comments from people actively replying to one another, usually organized in a tree structure. It’s more like a conversation.

https://en.wikipedia.org/wiki/Conversation_threading