Yellow, orange, and red bell peppers are essentially green peppers that have been allowed to ripen. Red bell peppers are fully ripe which means they are allowed to grow for the longest amount of time (hence the usually higher price tag) and they will have the sweetest taste. Green peppers are picked sooner and have a slightly more bitter taste and the yellow and orange are in the middle of the spectrum. The longer the pepper ripen the sweeter they become and the higher the vitamin C content.