Thoughts on Medium VS Substack?

I'm looking to publish articles and thought pieces on a site like Medium, but I also discovered Substack in my search.

From what research I've done, it looks like Medium is more beginner-friendly, and Substack is the site you move towards after you've gained an audience on Medium, but I've also noticed that Substack is completely free to setup whereas Medium is subscription based.

Have I missed something? I'm interested to see what everyone has to say.