There are too many varieties of chili or pepper to count; but there are surprisingly few that are known as bell pepper, Capsicum annuum. They are the select few that lack capsaicin, which is what makes others so distinctly hot and spicy. Most are quite mildly flavored. Green bell peppers, particularly those that are green because they are unripe, are generally more bitter and less sweet.
Bell peppers are warm season vegetables that get planted at the same time as tomato and eggplant, which they are incidentally related to. They are more productive where summer nights stay warm. In mild coastal climates, they are likely to start production later or finish production sooner than they would in warmer climates. They like warm sunshine, rich soil, and regularly watering.
The myth that green bell peppers are merely unripe red bell peppers is not completely untrue. They all start out green, and red bell peppers are often used green. Furthermore, most green bell peppers eventually turn red if they ripen enough. However, varieties that are grown as red bell peppers are different from varieties that are grown as green bell peppers. Orange and yellow bell peppers are increasingly popular. Purple, brown and white bell peppers are still rather rare. Red and green are the most productive and easiest to grow. -- Tony Tomeo