FYI Public Service Announcement: Pepper is a seed from various sub-species found originally in the middle east. Usually ground to more closely regulate the flavor and heat. While there were other spices available, pepper along with salt were the mainstays of the spice industry for thousands of years. Often salt and pepper were used in lieu of money.
Chilies on the other hand is a new world discovery. Chili Pepper is a misnomer. The heat from chilies comes from the chemicals capsaicinoids or simply capsicum. Very different from the heat producing chemical in seed pepper piperine. So, something as simple as what is commonly called a Bell Pepper would more appropriately called a Bell Chili. Same with all the other members of the chili family. The capsicum in a chili is not contained in the skin or the meat immediately under the skin or in the seeds, but within the connective tissue between the meat and seed. If you've ever dissected a chili, it would be the light fleshy material called oddly enough the placenta.
The Scoville Scale is the measure of the relative heat of a particular chili. For example, a bell chili would be a zero on the Scoville Scale. Banana chili would rate 100-1000. Jalapeno would be 3500-10,000. Cayene 30,000 to 50,000. The scale goes into the millions. Seems like every few weeks a new hotter chili is found.