The main difference between paella and risotto is in the preparation. Paella is much more hands-off. All you have to remember with paella is never to stir it. After you add the broth, bring it to a boil, reduce the heat to medium, and let it simmer away. In paella, the rice remains quite separate and creates a crust at the bottom.  Risotto has a higher starch content, and by stirring it for 20 minutes, the starch is released in the pot and creates a creamy, rich consistency.