I know you are Scottish, Ishbel
, but many viewers are American or non-European, at least.
Yes it is known as Chinese cinnamon, as it came/comes from China, the Indian word for it is dal chini, meaning Chinese wood, I believe. It contains much more coumarin than Sri Lankan cinnamon, and has a more savoury flavour because of it. I use only cassia in savoury dishes.
The difference in appearance is obvious. Cinnamon is sold in tight curls and is a light tan colour whereas cassia looks like the bark of a tree, which it is, of course, and dark brown.
These two are always being mixed up, even by Indian people. I suppose its what one has been used to, or taught. Anyway, may I suggest you think about using cassia, it has a darker note, and, IMHO, better at being integrated into a savoury dish. However, if using it, add it at the oil stage to extract maximum flavour, like all very aromatic spices.