The midsoles are different. The 14 is using the highest grade of midsole foam which is more resilient.
The wave technology in the Wave Rider 14 is consistent with previous models, allowing for a smooth heal to toe transition for neutral runners. The shoe continues to stay well ventilated with a mesh outer. I have always found a well ventilated running shoe to be nice, except when testing it out in the snow and your feet can get a wet pretty easy. One of the newer technologies used in the Wave Rider 14 is the Dynamotion Fit which is the padding and fabric surrounding the heel cup. In essence, this helps keep your foot in place in the shoe while running, helping keep the heal from coming out of the shoe which can sometimes cause blisters.