I have ridden both actually side by side switching between the two bikes multiple times during a ride. I must say there is a fairly significant difference. The SL is constructed of a different carbon which I believe they tout as lighter than the advanced carbon. Aside from the differences in carbon, the main difference I noticed was stiffness. The SL frame puts every ounce of power into the road and is a sprinting machine. I believe much of this difference is in both the carbon and the massive rectangular downtube. I ended up going with the SL due to the differences but the advanced, if riding it stock is actually a lighter complete bike and a great bike for the price.