Jim, Tritium night sights are a bit better in low light and dark environments as the tritium capsules actually glows via production of light. During the day tritium sights appear as regular sights. Fiber optic sights gather available light and appear brightest is full daylight and are dimmer but visible in low light scenarios. In pitch black fiber optics gather no light and are way less or not visible at all. There are Hybrid Sights that give you the best of both worlds.