Typically the economy chassis have less adjustability and cheaper components. Top of the line karts usually have billet pedals with very little play in the mounting pivots and are fully adjustable, they feature all magnesium components like hubs, sprocket carriers, bearing cassettes. And they usually have much better brakes and bearings, resulting in a chassis that is more free rolling and faster. All the latest enhancements and newest frame designs are used on the top of the line karts. The economy karts are usually an older frame design, have standard components with much less or no adjustability and are designed for entry level karters.