One of the main differences between gelato and ice cream is its airiness. Gelato contains less air than ice cream, which is why it has such a dense consistency in comparison to its dessert cousin. To achieve the correct amount of air, you need to churn for the correct amount of time.
Gelato -- and ice cream, too -- won't look like the frozen, creamy dessert you're used to when it's done churning. It needs to spend at least two hours in your freezer before that can happen. Churn it only until it looks like a thick custard, not firm ice cream. Store it in a shallow container (and cover with plastic wrap under the lid) for best results.