All Bell Peppers Are Essentially the Same
Red, orange, yellow, and green bell peppers are all the same type of bell pepper, they are just in different stages of ripeness. Bell peppers start green and then ripen to yellow and orange and then finally to red.
With that in mind, different strains of bell pepper are bred to favor a color. So some strains a bred to keep from ripening and stay green, while others are bred to ripen to a red.
FACT: The vitamin contents of peppers change as they ripen, so for example red bell peppers have 11 times more beta-carotene, about two times more Vitamin C and ten times more Vitamin A than the first-harvested green bell pepper.