A navel orange is a type of citrus fruit characterized by a small secondary fruit embedded at its blossom end, resembling a human navel. It is seedless, sweet, and has a thick, easy-to-peel skin. In contrast, a Valencia orange is a variety of sweet orange that is typically larger than a navel orange. It has a thinner skin, more juice, and a slightly tart flavor. Valencia oranges are often used for juicing or eating fresh.