I thought brackets ( eg '[' or ']' ) are Clojure syntactic sugar. I don't recall much use of them in Common Lisp (or Scheme), though I'm happy to be shown the error of my ways.
AFAIK, you are correct. In Clojure, square brackets are used for vector literals. Furthermore, Clojure uses vectors in some places (e.g. parameter lists in function definitions) that most Lisps use regular lists in order to help make those things more visually distinct.