In the following accepted answer you can find the ingredients of the Indian curry powder. I usually cook with Indian curry powder, however, I recently received some Sri Lankan curry powder. The aroma is different when I use Sri Lankan curry powder, (in my opinion, better,) and it tastes different too. Does anyone know the spices used in making Sri Lankan curry powder?
Most of the recipes I've made for Sri Lankan curries typically have pandan, dry curry leaves, fennel, green cardamom, mustard seeds, cloves, cumin, coriander & black peppercorns.
There are two main types of Sri Lankan curry powders, yellow and black. Yellow curry is much like stereotypical Indian curry powder, whereas black curry powder is roasted.
Also, in my experience, Sri Lankan curries tend to be hotter than Indian (and more than one friend of Indian heritage has expressed surprise that I enjoy Sri Lankan food, since they find it too hot.)