There are many types of onions that can add flavor and wonderful aromas to any dish. The main different types of onions are the common yellow onion, red onions, and white onions. However, other kinds of onions such as scallions, leeks, and shallots are widely used in the kitchen. Even though onions are a pungent type of vegetable commonly used in cooking, there are also many sweet varieties that you can enjoy eating raw.