Gelato is made with milk, not cream. But unlike ice cream, gelato machinery whips almost no air into it, resulting in a very rich texture and dense consistency. This allows the much lower-in-fat gelato to often surpass the taste of ice cream!
Gelato typically contains 2–8% fat depending on the folded-in ingredients. American ice creams contain more fat, ranging from 16% to 30% since cream is used. High end ice creams use even more cream, but high end gelato combines higher quality ingredients with milk, water or even soy milk.

(Grazie, Steve P.)