As above, you're getting the full "Cadillac" Remington Police gun versus the Wilson gussied-up Express gun, AND you're getting a better gun for less money.
The Wilson is, in my opinion not worth the money, especially compared to a genuine Police gun, which is the absolute top-of-the-line in defense shotguns.
The Police is typically a smoother operating gun right out of the box, has a much smoother finish, inside and out, and has no "issues" with quality.
In short, you can actually spend less money and get a better gun with the Police.
You'll hear some buyers of the Wilson who have some complaints about various things.
You'll very rarely to NEVER hear a Police gun buyer with any complaints at all.
Most Police gun buyers RAVE about the quality, "feel", and strength of the 870P.
The Wilson is a nice gun, over-priced.
The Remington 870P Police is a tank.