We certainly have no shortage of frozen dessert options! I know you've heard of the five above, but perhaps you're a bit unclear as to the difference? In ascending order of calories, here's a simplified breakdown:
Granita - Sugar-syrup base plus pureed fruit (or coffee or wine). No butterfat. Similar texture to shaved ice. Can be made without an ice cream machine.
Sorbet - Similar to granita, but whipped, which breaks up the ice crystals and makes the texture lighter than granita. No butterfat. Made in an ice cream machine.
Sherbet - Sugar-syrup base plus pureed fruit, and a bit of butterfat (no more than 2%). Made in an ice cream machine.
Gelato - Mostly milk, some cream (butterfat content generally 4% to 14%). 10% air. Made in an ice cream machine
Ice Cream - Mostly cream, some milk (butterfat content generally 11% to 18%). 30-60% air. Made in an ice cream machine.