Cassia cinnamon
Ceylon cinnamon
The latter is what this article is calling "real" but they are both real. Ceylon originates in India and is used in Indian cooking. Cassia originates in SEA/China Asia and is used in recipes there.
They are simply two different varieties of the same tree and they are both cinnamon. In fact there are many more varieties than just that two, same as with apples, tea, coffee or any other plant and it makes no sense to designate only one variety of cinnamon as "real". They have different flavors and neither is better.