They are actually similar in construction. Both use the same thickness leather (2.6 - 2.8mm thick). Both are lined with Gore-Tex. Both use the same lasting board. The difference is in the sole. The 520 uses the TPS (triple power structure) which uses shock absorbers in the areas of the foot that receive the most impact. The sole of the 200 uses 3 different densities of PU that are strategically located for different things: stability, comfort and shock absorption. The 200 has pulleys in the lacing system, and are a bit lighter in weight than the 520s. Lastly, the 520s have a deeper lugged sole. I would give a slight nod to the 520 as being a bit heavier duty.