Clojure def vs defn for a function with no arguments

Question

I have written a program in clojure but some of the functions have no arguments. What would be the advantages of coding such functions as a \"def\" instead of a \"defn\" with no

Answer 1

(def t0 (System/currentTimeMillis))
(defn t1 [] (System/currentTimeMillis))
(t1)
;; => 1318408717941
t0
;; => 1318408644243
t0
;; => 1318408644243
(t1)
;; => 1318408719361