Chilli powder is part of the nightshade family of 'Solanaceae' along with tomatoes and eggplant. It is sometimes used interchangeable with cayenne pepper but cayenne pepper is a vegetable that is ground into powder while chilli powder is a mixture of several dried chillies and herbs and may have cayenne pepper in it.
This chilli powder is around 10000-15000 Scoville heat units (SHU). The Scoville scale is the measurement of the pungency (spicy heat) of chili peppers or other spicy foods.