Gelato is the Italian word for ice cream, derived from the Latin word “gelātus” (meaning frozen). It is an all-inclusive term that loosely translates to ice cream but also includes anything from sorbet and yogurt to custards.
Compared to American-style ice cream (that is one made with egg yolks, as is basically the new standard in home recipes and commercial products), gelato has less fat in the base and less air churned into it during the freezing process.
Gelato, by comparison, uses more milk than cream, so it does not have nearly as much fat. Additionally, it usually-but not always-uses fewer (to the point of none) egg yolks, another source of fat in custard-based ice creams.It is churned at a much slower speed, which introduces less air into the base-think whipping cream by hand instead of with a stand mixer. That is why it tastes more dense than ice cream.
You can make both gelato and ice cream in your ice cream machine, remember, air is only one of the differences between them.