Although Oriel owners would be able to better explain the difference. Surprisingly, even guys at 3S said that they are same. This meter would illuminate the moment the door is opened and/or the key is inserted eliminating the need of switching on parking lights to get the meter illuminated. A neat feature but not that big enough to make a great difference or impact. Relax. Whatever you are getting is better than anything in the market.
Some info I got off the internet (Cut / Paste / Copy):
[I]The face of your guages either dim or lighten the display in various lighting conditions you are in. It allows you to have an optimum view of your display cluster. If you pay close attention to your guages esp. in direct sunlight (sun shining into the car from behind) the guage face has a blue tint. It's an electrochromatic system that works similarly to your auto dimming mirrors. The light sensor for this is located right beneath the high center mounted stop lamp on the rear deck of your car.