The only similarity that Elixir honestly has with Ruby is clean syntax and general emphasis on productivity. Everything else is different. Same with Phoenix. On the web side of things it has routes, controllers and views...but there's no magic involved. It's all very clear, explicit and flexible in how it does things. The view layer is honestly one of it's biggest strong points because the way it's handled is the core reason for all of those "My site was faster without caching" articles...but you don't have to work differently to enjoy those gains.
Big Nerd Ranch did a solid write up on the ins and outs of why.
https://www.bignerdranch.com/blog/elixir-and-io-lists-part-2...
This Choosing Elixir for the Code post that came out last month does a really good job of emphasizing a lot of it.
https://pragtob.wordpress.com/2017/07/26/choosing-elixir-for...