The only difference tween the Express and 870 is money.
Wingmasters have the same actions, but the parts in the Express are rough, where the parts & wood in the Wingmaster have received more polishing, attention, bluing which results in a much smoother action but more cost.. The wood is Walnut in the Wingmaster where the wood in the Express could be any number of hardwood or synthetic, whis is not all bad.
I have had a 870 Wingmaster magnum, which shows how old it is, but stuck a synthetic stock on it. All 870's actions have been magnums for years, but only recently all have 3 inch chambered bbls. (Recently is a comparative word meaning anything.)
I like the 11-87, a little heavier, but less recoil and not that much more. Assuming you are young, a little weight wont hurt anything. Age makes all guns heavy. Even my Beretta ou lightweight seems heavier than when I bought it for field carry.