I guess you could say I live an odd life, when twice in one week the random subject of red bell peppers comes up. Specifically the question, “Are red (or yellow or orange) bell peppers a different variety than green ones?”
Years ago, I worked for a company in Gilroy that developed both flower and vegetable varieties. Bell peppers happened to be one of them. They not only did the research, plant breeding and field trials, but they also sold the seeds. The bell peppers, when mature, always were red, which meant they were ripe.
They went through various stages of color along the way, starting out green, then yellow, then orange, then red. If left on the plant longer than that, they normally would change once again, to a purple-brown color. The red ones were priced higher in stores because it costs more for farmers to prolong harvest.
The more I try to find out about this or that pepper the more confused I get, as many of the yellow, orange, red and purple/brown pepper seeds or plants are marketed in such ways as to suggest each color is due to a different type of pepper. There are several different varieties of bell peppers, with certain characteristics (like shape, thickness, short or long growing season and disease resistance), but I think if you are mainly concerned about which stage of ripeness you prefer, I am betting they all go through the same stages. If you are a bell pepper farmer or expert, feel free to contribute your knowledge...