The main difference between the 2007-09 and the later years up until 2014 is going to be the power output. The S197 chassis didn't change very much at all during those years though Shelby made refinements during that time to the driveline, suspension, steering, and brakes. The same transmission was used albeit with some minor tweaks as time went on.
2007-09 is essentially the same car.
2010 got more power, the facelift inside and out, and some minor suspension tuning.
2011-12 got marginally more power, new and better steering, further suspension improvements, stability control, was a tad lighter, and there was an optional Performance Package.
2013-14 got much more power, strengthened driveline, better cooling, bigger brakes, a minor exterior facelift, adjustable launch control, even better optional Performance Package, and a Track Package.
In addition to this stuff there were more specific things added as time went on but this is the meat and potatoes of improvements.