Series 3 is our entry level frame which is perfect for small office/home office, it has a 3-year warranty rather than 5 year. The electronics and motors are 100% Chinese as is the frame manufacture. Aesthetically the frame has a different, less European look with slightly more gloss to the powder coat. Functionally it is largely the same as a eries 2 desk it is in the finish and refinement that the cost difference lies.
The Series 2 is a more commercial desk frame and has a better quality of metal work and powder coating and upgraded electrics and comes with the 5 year warranty. The drives and controls are made by Ti-Motion in Taiwan and the powder coating is full matt. The desk has a long pedigree and has longevity rates based on a large number of units sold into the market.
For a full analysis see this page https://www.gostand.co.uk/pages/desk-comparison