Found a good thread on one of the forums comparing the different Align 450 Class helis so far.  450S vs 450GF vs 450SEv2 Vs 450Pro.

There are lots of pics showing the differences between the 4 helis, the popular 450 class helis have come a long way and its not stopping yet with Align releasing the upcoming 450 sports version soon. Interestingly, we can see how the design and packaging has evolved from squarish blocks to more curvy lines mirroring that of cars.

See more from the thread here.

Pictures coutesy of 5imx.com