"Wide noodles" is a kind of noodles with rectangular cross section and made of flour, which is the staple food product in northern wheat producing areas. And "river noodles" are made of rice, which is a very popular staple food in rice producing areas.
Noodles are mostly unheated, that is, they are basically "raw" and are directly pressed with noodles; Rice paste must be steamed and sliced before being cut into strips. As soon as it is made, it can be eaten directly with seasoning, or it can be conveniently dried and preserved, and then cooked before eating.