The only difference I can see is the color, but their website lists them as separate products. http://www.lightandmotion.com/choose-your-light/urban
Just the color. The products are identical. Light & Motion lists their different color variations as separate "products", probably due to some limitation of their store site engine.
Note that there is an Urban 800 Fast Charge version, which in addition to coming in different colors, actually is a different product physically.