Trying to buy pasta is one of the hardest things in Italy. Enter any supermarket or shop and you will find shelves full of different kind of pasta. In larger supermarkets you can choose between at least 50 different types of pasta. IF you can choose.
Obviously the shape doesn't really matters so much for the taste, but it makes some difference on how you will have to eat for the final food. And that will change your experience of eating.
Take the
fettuccine for example. You could do the same thing with the penne, and it would still taste good, but you wouldn't be able to twist the pasta around your fork and take a big bite in it.

Besides, the fettuccine is made with eggs, the penne no.
Sometimes the shape matters, sometimes it doesn't.
There are different kinds of fettuccine. Big, medium, small, longer, shorter - in this case there's no difference between them. Usually you can substitute one with another. Your "eating" experience will be slightly difference, but not the taste of the food.
There are different kinds of penne too. Some are shorter, some end in a straight cut, others in a diagonal cut. Again, they are the same.
Then there's the smooth version of the penne, without ridges. They have the same taste, but you can't replace one with another.
I'm sure everyone's familiar with the carbonara. You think it's made with spaghetti? You're wrong. While the spaghetti alla carbonara is a famous dish between the italians too, I know that most of the people in Rome would prepare the carbonara with the penne. It makes sense too.
The spaghetti is good for thin sauces, the penne is better for thick sauces - the ridges are there to help the sauce stick to the pasta.
Well, in Rome you don't use cream for the carbonara. Eggs, bacon, parmiggiano and pepper. Here the ridges help the egg to stick to the pasta when coagulating, so you actually imbue the pasta with the "sauce", instead of only coating it. It makes a lot of difference. They will give you the sensation of a different taste.
I am not a big pasta eater myself, but I can't wait to to be back in Rome and eat some good food.
Next week I'm eating carbonara and pizza every day.
