It's just the shape. They only taste different if you get whole wheat ones, or flavored ones like spinach, tomato, squid ink, or things like that. They also hold sauces differently, so pasta with big gaps/grooves (like rotini or penne) hold chunky sauces better than smooth ones (like spaghetti, which is better-suited for smooth sauce). It's just nice having some different options around the house; sometimes I want a pasta shape for a good meat sauce that isn't rotini... Plus it's also a nostalgia factor - pappardelle is basically just giant fettucini, but just knowing I'm eating pappardelle instead of fettucini makes me feel warm and fuzzy. :)