Red and green peppers are the same species of plant at different ripeness stages, with distinct flavor, nutritional, and culinary differences. Green peppers are harvested before fully ripening, while red peppers are left on the plant longer to mature. This ripening process fundamentally changes their characteristics.
Flavor is the most noticeable difference: green peppers have a grassy, slightly bitter, and more vegetal taste, while red peppers are sweeter with fruity undertones. This sweetness develops as sugars accumulate during the ripening process. Green peppers also have a firmer, crisper texture compared to the slightly softer flesh of red peppers.
Nutrionally, red peppers contain significantly more vitamin C and beta-carotene than green peppers due to their extended ripening time. Red peppers also have higher levels of lycopene and other antioxidants. Green peppers do contain nutrients, but in lower concentrations.
Culinary applications differ accordingly: green peppers work well in dishes where a sharper, more assertive flavor is desired—like stir-fries, fajitas, or salsas. Red peppers are preferred for eating raw, roasting, or in dishes where sweetness is an asset, such as pasta sauces or side dishes. Green peppers are typically less expensive because they're harvested earlier and require less growing time.
Both are the same plant (usually Capsicum annuum) and equally nutritious in different ways. The choice between them depends on your recipe, taste preference, and budget rather than any fundamental difference in safety or quality.