Gelato is usually made from milk and ice cream is usually made from heavy cream. Gelato has less air beat into it during the churning process and ice cream has a lot more air beat into it during the churning process. Because of the excess air in icecream, it has to be frozen at a lot colder temperature than gelato does. Gelato is served at a warmer temperature, thus it seems a lot more flavorful. Also because of the air issue, gelato seems a lot creamier than ice cream does because it is more dense. Gelato is lower in fat but tends to have a lot more egg yolks in it which makes it higher in cholesterol. Lastly, because gelato is from the mediteranian and ice cream is from england/the US, the flavorings tend to be different (i.e. you won't find fig icecream or oreo gelato). Hope this helps.
I believe there is also a difference in ingredients used (not just flavourings)
aha, here is a dirrect quote from:
"For those wondering how gelato is different than ice cream, the basic differences that I have found (in all of my scientific research regarding gelato over the past few years - I mean minutes) seem to be the "overrun" (or aeration) of gelato, which is a lot less then ice cream - resulting in a more solid, richer texture (air content in gelato can be as low as 15%, air content in ice cream can go up to 50%). Another main difference is that it is not frozen as solidly as ice cream, giving it a smoother, creamier feel. The amounts of basic ingredients found in both - milk/cream, sugar, sometimes eggs - differ slightly also, with gelato having only milk (or water, depending on the flavor) or milk and a little cream, which not only means less fat (2-8% fat vs.the16-20% found in ice creams), but it means the added flavorings are the real star, not the dense, fat-laden cream (nothing against fat-laden cream, mind you) which can cover delicate and subtle flavors. Another main difference (from industrial-strength "supermarket" ice cream, not the yummy stuff that comes out of your home ice cream maker) is that gelato is usually made in small batches, and usually made with seasonal ingredients, resulting in much fresher flavors."