To save you some grief...
Ground cinnamon is made from the ground up bark of cinnamon trees.
Cinnamon sticks are the bark of cinnamon trees.
HOWEVER:
In cooking, if it calls for the stick, there is a good reason. Cinnamon powder can drastically change the texture, flavor, and mouth feel of items calling for a stick of cinnamon. If you, for instance, make a drink of hot cider and put in cinnamon powder instead of the called for cinnamon stick, what you will have in the bottom of your cup is a slimy blob of cinnamon. Not to be gross, but it is like snot. The cinnamon stick will not do this and the flavor will be less intense than if you used powder.
So another thing to remember is that the powder is much more sharp in flavor than the stick. If a steamed rice recipe calls for a piece of cinnamon stick as it is cooking, use that and not the powder or the cinnamon flavor will over power all else.
It is like the difference in flavor of nutmeg or mace. They are both from the same source, (mace is the outer covering of the nut of nutmeg, not the shell but a light yellow covering over the nut) but mace is much much mellower.