Ramen noodles are basically made of wheat and long, elastic with yellowish colour. The dish was originally imported from China. However, it’s been changed and improved over the years, and evolved to popular Japanese food. There are countless varieties of ramen noodles which vary from thin and straight to thick and wavy nowadays. It also comes with various soup, such as soy sauce, salt and pork bones(tonkotsu).
Udon noodles are made by kneading wheat flour, salt, and water. They're firm chewy, and thick with white colour. One of the most common region of Udon was called Sanuki where is now Kagawa Prefecture. Sanuki Udon is served by many of the popular, nationwide udon chains. They can be eaten in a hot broth or with chilled dipping sauce.
Soba noodles are made of buckwheat flour and generally thinner than Udon noodles. They have a strong, nutty flavor and are usually light to dark brown-gray in colour. As 100% buckwheat soba noodles called Jyuwari Soba is tend to be brittle, many manufactures add some wheat flour when preparing their noodles. They are also served in noodle soups or dipping sauce like Udon.
There are also a few noodle dishes named soba (e.g. yakisoba, chukasoba or Okinawa Soba) however they're not made of buckwheat noodles. Yakisoba is another popular Japanese stir fried noodles. It is served with Yakisoba sauce, similar to Tonkatsu or Okonomiyaki sauce. though it is a little bit more like Worcester sauce and thinner. Yakisoba is usually fried with sliced pork and vegetables like cabbage and bean sprouts.