You're obviously not Italian...
Starting with the pasta itself (not how it's prepared), they use different ingredients. Italian pasta is usually made from high quality duram wheat, whereas American made pastas use a variety of flours, and usually includes eggs (rare with Italian pasta), which results in a softer cooked product. That leads to cooking differences, where Italians prefer firmer texture (al dente), whereas Americans tend to have it softer.
And then we have sauces. Italians usually keep it simple with a handful of ingredients, and Americans add milk/cream, sugar, cheese, or anything else that sounds good. Americans also go overboard on the sauce, so you get a lot less of the pasta flavor (yes, pasta has flavor, y'all need to add salt to the water).
And that's restaurant quality pasta dishes. It gets wild when you look at what's in those prepared meals in the freezer section.
I give pizza a pass because I don't like bread much (yes, I've had good Italian pizza), so loading up on toppings works really well. But I just don't like the mushy mess that is American-style pasta.