Chow explained it perfectly. Another easy way to tell it's a male is to wait and see if more balls form with that one. If you start seeing a cluster of them, it's a male.
Like Chow said, if it's a female, there will only be one with a hair coming out of the tip.
If you see clusters growing on one spot and a single calyx shooting a hair on another spot, it's a hermaphrodite.