Admittedly these two libraries are very similar; I actually hadn't heard about lein-fore-prob before (because it wasn't listed on the
leiningen plugin list wiki).
Because I started working on this without knowledge of the other library, it naturally has a few differences; one of which is that it creates separate files while lein-fore-prob puts all the problems into one file (unless multiple projects are created). Also, lein-4clj supports project-less template creation, allowing for a quicker workflow if a 4clojure user wants to quickly try out a solution using the REPL.
Anyhow, the two projects are similar and serve essentially the same purpose, so feel free to use whichever you'd like.
--Alex