Clojure/Script is more geared towards experienced developers who want the power to do whatever they want, in a conscise, expressive and customized way. They value flexibility, and immediacy, and like to know all the ins/out of their tools.

Elixir is a version of Clojure adapted more towards the Ruby model of making things easier for developers, giving people more focus, less choices, emphasising best practices, and overall offering something more familiar looking to most. It's complemented by Phoenix, which has similar goals, it is focused, directed, gives people a clear path forward.

They're both capable language, but you can see they have different focus and are geared towards people looking for different things.

So it depends what you're interested in:

If you like to do things from "first principles", meaning, you want to understand starting from birth and grow to adulthood, then Clojure/Script is for you.

If you prefer to do things "on the surface", meaning, you want to just get going with a project, see something get build fast, before you understand exactly how it all works, i.e., you want to start from adulthood, and slowly (or never) make your way back to the birth, then Elixir/Phoenix is for you.