Onions, shallots and leeks are all aromatic vegetables. The onion is a round multilayered vegetable which comes in a variety of colors, sizes ,shapes and flavor intensities. Red onions are sweet and colorful, Vidalia considered the sweetest onion, is white. Shallots are similar to onions, but a vegetable of their own. They have a flavor of onion and garlic, they are small and mild. Leeks look like over grown green onions. The white of the leek is used and the green portion is typically discarded. Leeks are very mild in flavor.