All types of cinnamon belong to the genus Cinnamomum, so there really isn't such thing as 'fake' cinnamon. However, there are two major categories of cinnamon: Cassia cinnamon (the 'fake') and Ceylon cinnamon (the 'true'). While both contain the same active ingredients, Ceylon cinnamon has the benefit of being low in coumarin. They also differ in flavor and most sutable application. Let’s start with the most commonly available version: cassia cinnamon.
All other than Ceylon types of cinnamon come from several different Cinnamomum trees (yup, cinnamon is hot an actual herb, it's made of tree bark). They're collectively referred to as cassia cinnamon. Before ground, in its bark-like form, cassia is rougher in texture, darker in color, and rolled in thicker sheets compared to Ceylon cinnamon.
There are three kinds of cassia cinnamon, based on their origin: Indonesian, Chinese, and Saigon.
Ceylon cinnamon is imported from Sri Lanka and Madagascar.
Ceylon cinnamon is tan-brown in color and contains many tight sticks with soft layers. Ceylon cinnamon is cinnamon is more expensive, harder to find. However, if you expect the expensive stuff to taste better than the cheap cassia, you are going to be disappointed. It has a sweet, almost-floral aroma.
As we mentioned at the beginning, Ceylon cinnamon contains less coumarin, a compound which can cause liver damage. However, you are unlikely to eat so much cinnamon for this to become an issue. Both the Ceylon cinnamon and cassia are equaly good for lowering the blood sugar and have anti-inflamatory and antioxidant properties. Both kinds are high in cinnamaldehyde, which is thought to be responsible for most of cinnamon’s health benefits.
The bottom line:
Don't give in to the thought that only the pricey Ceylon cinnamon has a 'true' flavor and comes with 'true' health benefits. Although there are differences among the various kinds, they're small enough that you probably won't notice them in whatever you're cooking. Choose your cinnamon by taste and enjoy it.