Pequin pepper is about 1-2 cm long and less than 1 cm in diameter. It is usually red or orange in color and has a thin, wrinkled skin.
Chiltepin pepper is about 1/2 inch in diameter. It is usually a bright red color when mature, but can sometimes be yellow or green. The skin of the chiltepin pepper is thin and smooth, with a slightly wrinkled texture. The flesh of the pepper is firm and spicy, with a distinctive, pungent flavor. Overall, the chiltepin pepper has a compact, ball-like shape and a bright, eye-catching appearance.
Chiltepin pepper and the pequin pepper are both known for their heat, but in terms of intensity, the chiltepín pepper is usually hotter than the piquín pepper. The chiltepin has a medium-high heat score on the Scoville scale, which measures the intensity of heat in chiles, while the piquín chile has a medium-low to medium heat score.
In conclusion, both pequin and chiltepin peppers are small and hot, but they differ in their exact shape, heat level, and place of origin.