For now at least, Substack has much, much better UI. Beyond that, Substack is currently positioning themselves as a platform/tool for content creators to creat

For now at least, Substack has much, much better UI. Beyond that, Substack is currently positioning themselves as a platform/tool for content creators to create their own brand and market to their own audience. If you aren't paying attention, you might not even notice that your favourite author was on Substack; they're functionally a spiritual descendent of the independent blogs of old (who might be running on MT or Wordpress or whatever, but weren't a "Wordpress blog by Joe Smith", but "Joe Smith's blog" (which happens to be on Wordpress). Medium has been positioning themselves as a content brand in their own right for some time; they have been undergoing relentless business model churn, but at various times they've had editorial teams, they've commissioned work, they've had writers on payroll, and they've had verticals or "editorial teams" or whatever such as OneZero, Forge, Marker, and Elemental. Those last I think were launched in 2019 and killed off in 2021; but functioned like magazines published by Medium with editors and staff writers. I'm not quite sure what todays strategy is, but it seems to still be focused on the publisher/magazine model where the brand is "Medium" and the author just gets a byline. You can see this approach in terms of features like theming, URL structures, support for custom domains, etc. (Eg, Substack supports custom domains; Medium recently ended their support.)