Oranges and Mandarin Oranges
Mandarin oranges visually differ from oranges by their size and shape, being smaller and less round. As part of the Citrus genus, both fruits are rich in phytochemicals such as flavonoids and carotenoids, because of which they express cardioprotective, antidiabetic, and anti-cancer qualities.
Overall, oranges win in the nutrition category; however, both fruits have various health benefits, and at the end of the day, the choice greatly depends on personal preference.
Oranges and mandarin oranges may seem like two different sizes of the same fruit. Belonging to the same Rutaceae family and Citrus genus, they do have a lot in common; however, they have their differences too.
It is assumed that orange (also called sweet orange) is a hybrid between pomelo and mandarins. The first mention of sweet orange in history was recorded in Chinese literature in 314 BC. Sweet oranges are the most popular type of citrus in the world.
Mandarin oranges visually differ from oranges by their size and shape, being smaller and less round. The taste is often sweeter than that of an orange. As the ancestor of sweet oranges, mandarins have naturally been around for longer.
Sweet orange usually has a thick rind, and inside, there is the white and bitter mesocarp, whereas the rind of mandarin orange is much thinner, and the lesser amount of mesocarp makes it much easier to peel. The endocarp of both fruits is separated into segments. Mandarin oranges contain much fewer seeds as opposed to sweet oranges.
People often use the words mandarin, tangerine, clementine, and satsuma interchangeably. However, tangerines, clementines, and satsumas are all varieties of mandarin oranges. Tangerines are bright orange and less sweet. Clementines are the most common type of mandarin oranges in stores; they are very sweet and easy to peel. Satsumas are also sweet and easy to peel; however, they are also easy to damage.
Resource: Food Struct - Orange vs. Mandarin Orange — Health Impact and Nutrition Comparison