The JX was the first year model and had a towing capacity of 3500 lbs. The following year Infiniti changed all model names, hence, the JX35 is now the QX60. The difference was the changing of transmissions to allow a 5000 towing capacity. Not much else has been changed through model year 2015. There was a transmission problem experienced late 2013 through 2014 which has been corrected. It caused a shuttering at low speeds. The 2016 model is slated for later this year and has a grill face lift, daytime running lights and more insulation. There may also be a change in the telematics system similar to on-star because the previous models use the AT&T 2G Network which goes away at the end of the year. Thats pretty much it.