From a design point, it’s kind of apples and oranges, really. From a weight, geometry and design standpoint it is a better frame. Build quality completely depends on other factors that are beyond our, or in fact Mongoose’s control… How much is the shift supervisor getting mongoose bicycle for running the production line 15% faster than it should be running? Did the tube fit finisher get laid the night before? Typically you see it when a frame tube ruptures or a weld breaks, but sometimes it shows up in odd ways, like a frame having the wrong brackets, etc.
This is referred to as the “Slack”, when riding backwards you must keep your feet positioned within the slack, if your pedals rotate too much the drivetrain will engage and your pedals will start to rotate. The smaller the slack, the harder it is to keep your pedal positioned within it while riding backwards. This means that certain tricks are harder to perform, especially those that rely on pedal pressure, for example Tire Taps.
Most experienced riders know their preference, but if you’re new to the sport it can be difficult to know which choice to make. The first Mongoose BMX bike had several unique features. The first brake tabs were two pieces of metal welded together, and they were rectangular. Later, the brake tab became a little bigger, was a single piece of metal, and was oval. The caliber brake on the first Mongoose BMX bikes was also two sheets of metal, and it was thicker than on later models. The seat tube was longer on the first Mongoose BMX bikes, and the frame flared where the seat post joined it.
Youth freestyle bikes are sized depending on the diameter of the wheel staring at 12” all the way through to 18”, at a 20” wheel the bike is considered an adult size. Adult freestyle bikes are sized on top tube length, a 18.5” top tube is extra small for younger teenagers who have just moved up to an adult bike, a 20” top tube is small, 20.5” a medium and anything over a 21” is considered large. Although this may seem like a brilliant feature, it does come at a price! Freecoaster hubs feature a “Slack” before engagement while pedalling forward. This means that you can turn the crank a set amount (Usually an adjustable amount) before the drivetrain engages.
When I said Originally, I was referring to before the 1983 redesign. I.E, the early Motomag, Team, and Supergoose with the first gen drop outs and the double front gusset. The Motomag frames mongoose racing bike had a Cro Mo front triangle with a mild steel rear. A few posts up there is a link to the new Mongoose bikes that are supposed to be as good as anyone else’s and are not walgoose editions.