Differences between prismatics schema and clojure.spec

Question

I have just recently started to learn some clojure and in order to make something like types (more like contracts) for validations etc, the go-to solution is a library named schema.

Recently I learned that clojure 1.9 however will have something similar named clojure.spec

Can anyone please tell me the differences between them?
When should I use one or the other, pros and cons, etc?

Answer 1

Eric Normand did this comparison, but as already pointed out you should definitely check the rationale, and there is also the guide and a podcast where Rich Hickey talks abouts clojure.spec.