While rice can be cooked in soup, some varieties of rice produce a better result than others in terms of texture and resilience.
Rice can be cooked in most water-based liquids, absorbing the flavors around it. This makes it an ideal ingredient for adding texture and substance to soups.
White rice is the endosperm layer with all outer layers removed. Removing the chaff but keeping the bran and germ gives us brown rice.
During cooking a chemical process called gelatinization takes place. This leads to a softening of the rice as starch granules absorb water from the surrounding liquid and lose their crystallinity.
If you continue to cook and stir rice after gelatinization, you can cause another process called pasting.