I own both a Maverick 88 and a Mossberg 500. the Mav has twin slide rails, as does the Mossberg. Only difference is the way the foregrip mounts to the rails. I actually have the Mossberg rails and foregrip installed on my Maverick. The synthetic stock on the Mav is not cheap, although I did replace it with a pistol grip and 6 point stock. Of the two, I use the Mav 88 more. Why? The Mossberg broke. The Mossberg has become the canibalization gun, really just a place to store my extra parts and barrel.
I use my Mav 88 for hunting with the long barrel and HD with the 18" barrel. Mossberg barrels, and virtually every other part, are interchangeable. Other than the foregrip difference, the only other recognizable difference is the safety. Mav 88 has a crossbar safety on the trigger guard, Mossberg has theirs on the top of the body. While virtually the same, and price difference can be negligible, I've had absolutely no issues with my Mav 88 since the day I bought it. My Mossberg, on the other hand, bought used for $40, sits unused. I sometimes regret spending what little I did for it.