I was able to get a little information on the TG3 website. As far as I can tell, the Decks are identical to the cop car keyboards, except for cosmetic differences - translucent cases, keycaps, etc.

Are there any big differences that I'm missing?

There are more than just cosmetic differences between the Deck and the “cop car” keyboards. The “cop car” keyboards have aluminum sub-chassis, splashguards to protect against spills, rain, and other foreign material entering the keyboard, and special printed circuit board assemblies for better noise immunity to electrical interference caused by high power police radios operating in very close proximity to the keyboards. All of these things would add significant cost to the Deck keyboard. The splashguard also makes the keys feel very “stiff” and wouldn’t be suitable for fast-action gaming.

The cop car keyboards are about 3 times the price too However I believe the LED/Backlighting used in both is identical.