Clojure is functional to the core and innovates a lot of areas, while other Lisps are more multi-paradigm and slant towards an OOP style. If you want to work universally with persistent data structures in your code and the libraries you use, Clojure is really the only option. Clojure also modernises Lisp syntax slightly (and a bit controversially) by getting rid of lots of parentheses and introducing new styles of parens for the core built-in data structures: ( ) [ ] { } #{ }. There's a bunch of other stuff, but really, Clojure is significantly different from other lisps.

The Rationale page on clojure.org has a pretty good rundown: https://clojure.org/about/rationale