The difference between a $25,000 vehicle and a $40,000 vehicle can be essentially just the finish. Same frame, engine, transmission, everything that makes a car a car and and SUV an SUV from a motion control standpoint may be the same, but the cash for a higher level of finish is substantial.
It isn't much different with firearms. An Express goes bang just as well as an 870 Wingmaster, it is just finish. The receivers are all made from a solid block of steel and the barrels are all made from 4140 steel . . . and, they are all made in Ilion, NY, with the same machines by the same people.
Some people claim their old Wingmasters are "smoother." Of course they are. After an 870 gets shucked 15,000 or 20,000 times, they all get smoother . . . old or new, Express or Wingmaster.