The main difference between noodles and macaroni or spaghetti is that, in addition to flour and water, noodles contain eggs or egg yolks. Noodles can be cut into flat, thick or thin strips of various lengths, as well as into squares. A wide variety of noodles is available in markets, including those enriched with vitamins and minerals, and colored noodles (red tinted with tomato paste or beet juice and green with spinach). Noodles are sold fresh (these should be refrigerated for no more than three days) and dried (best stored in a cool, dry place for no more than six months).
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.