1 The cochlea, dedicated to hearing; converting sound pressure patterns from the outer ear into electrochemical impulses which are passed on to the brain via the auditory nerve.
The Scoville Heat Scale. The Scoville scale is a measure of the 'hotness' of a chilli pepper or anything derived from chilli peppers, i.e. hot sauce. The scale is actually a measure of the concentration of the chemical compound capsaicin which is the active component that produces the heat sensation for humans.
Aside from the obvious color and flavor differences, they simply come from a different species. A Cayenne chili pepper looks like this. Its Scoville rating (a system the measures the spiciness in capsaicin-based peppers) is around 30,000-50,000 Scoville units (pretty spicy, according to my palate). By comparison, the hottest chili in the world is ~2 million Scoville units.