What are the main differences between spaghetti and spaghettini in terms of size, texture, and best pairings?

Spaghetti is thicker and longer than spaghettini, which is thinner and more delicate. Spaghetti has a chewier texture, while spaghettini is more tender. Spaghetti pairs well with hearty sauces like bolognese, while spaghettini is better suited for lighter sauces like aglio e olio.