Look for both meats in well-stocked supermarkets, Italian grocery stores, or specialty food shops.
Prosciutto (pro-SHOO-toh): To Italians, prosciutto means "ham"; cooks in America use the term to refer to a type of ham that has been seasoned, salt-cured, and air-dried (rather than smoked). The process takes at least nine months and results in somewhat sweetly-spiced, rose-colored meats with a sheen. Parma ham from Italy (prosciutto di Parma) is considered to be the best. Sliced prosciutto dries out quickly and should be used within a day or frozen for longer storage.
Pancetta (pan-CHEH-tuh): Italian-style bacon that's made from the belly (or pancia) of a hog; unlike bacon, pancetta is not smoked, but instead seasoned with pepper and other spices and cured with salt. Pancetta is generally available packaged in a sausagelike roll. In a pinch, substitute regular bacon.