The big difference between these two peppers is simply age. They are the same pepper, just a green jalapeño is picked early in the ripening process, while a red jalapeño is left on the vine to mature. During the ripening, jalapeños, like other chilies, turn red. The process takes time so many jalapeños end up multi-hued, various shades of green and red during the aging process. And the same pepper plant may have some green, some red, and some various hues of each.
