[VoxPelli]

It's different because the blogosphere was all about posting blog posts whereas social media, which started out being called "microblogs", is about posting other types of material and doing other kinds of social interaction.

In essence the indieweb enables posting all of those types of content, and making all of those interactions, through ones own site, in a way that can give a user experience comparable to eg. Twitter.

It's the classic pendulum of innovation – Twitter and friends spearheaded new interactions and UX that once proven can be standardized and implemented in the open, just like the blogosphere was an open implementation of the pattern of news sites.