Chili and pepper are not the same thing however people just refer to chilies as peppers interchangeably.
As far as I'm aware the difference is that peppers contain pipirine coming from the piper plant(such as black pepper, long pepper) whereas chillies contain capsaicin coming from capsicum plant and this is mutually exclusive.
This scoville chart https://www.pinterest.com/pin/148196643973566417/ shows bell peppers as containing no capsaicin so why is it in the list and is it considered a chili?
I'm confused Please clarify.