Just like people, pasta comes in all different shapes and sizes. And there's a reason for it. For one thing, the different shapes represent the region the pasta hails from, but more importantly, these shapes and sizes allow you to pair the pasta with the right kind of sauce to get the best flavour.
Spaghetti should be paired with simple, lighter sauces like tomato or garlic and olive oil. This is so the delicate noodle strands will be evenly coated and won't get weighed down.
Bolognese is usually paired with fettuccine or tagliatelle because these noodles are flat and heavy and carries the sauce much better.
The “cream” sauce is mostly flowers of rapini, which are sweeter than stems. It's lightly pulsed with a pesto-like texture.
Stuffed pastas are typically paired with light sauces so you don't lose the flavour of the stuffing.
Hearty vegetable sauces, or baked cheese dishes, are best for penne pasta because there is more potential for the sauce to get caught in the "tube" or cling to the noodle.