All three are types of cured pork, which means that salt is used to draw the moisture out of the meat to preserve it, and then the meat is left to sit for a while to age.
Many pork products come from the belly of the pig, but guanciale,
pronounced:(GWAN SEE ALL EEE)
It has a strong, rich, intense flavor and is a celebrated delicacy in Central Italy. To make it, first the cheek is rubbed with salt, peppercorns and thyme, then it is hung to air-dry, and is ready to eat after three weeks. It’s rather fatty, but once rendered, you’re left with a strong, rich, porky flavor.
Pancetta, comes from the Italian "pancia" or belly, and is often called "Italian bacon."
That’s not quite accurate because pancetta is not typically smoked the way American bacon is. Like guanciale, it’s salt-cured, but it is seasoned with different spices that can include nutmeg, pepper, fennel, dried ground hot peppers and garlic, and then air dried for three months.
Pancetta is sold either rolled or in a slab.
It gives dishes a wonderful pork flavor without the overwhelming smokiness of bacon.
Prosciutto is the Italian word for ham, and describes a salt cured whole leg of pork that has been aged for up to two years. Proscuitto production takes just four ingredients: pork, sea-salt, air and time. There are no other seasonings. Nearly 70 percent of all prosciutto is Prosciutto di Parma, which comes from its birthplace in Parma, Italy. Prosciutto di San Daniele from Italy’s Friuli-Venezia Giulia region is also well-regarded.