Most cinnamon sold in supermarkets is cassia: thick, hard bark with a strong, sweet heat. Ceylon cinnamon is thinner and rolls up in many papery layers; it tastes softer and more citrusy.
We stock both (sample). Cassia stands up to long braises and spiced breads; Ceylon is the one for rice pudding, fruit and our garam masala.
If you are not sure which one a recipe means, bring it in and we will grind 10 g of each for you to smell.