Udon and Ramen; what's the difference?

Similar to Ramen, there is another kind of Japanese noodle, Udon.
Both are made from flour.
What is the difference?

The material of ramen is hard, or sometimes very hard flour like to make bread, while one of udon is all-purpose flour.

That is why ramen is more elastic and has clear sensation when you cut it with teeth.
On the othe hand, udon has soft sensation, and get more crunch after making kread dough.

Aside from flour, ramen includes egg and a special composition of minerals.

So, the taste of ramen is totally different from one of udon