The answer to your questioin is yes. There are many differences. The main difference is the height of the heatsinks and fans. The 1283 models are 160mm in height and use 120mm fans. The 963 models are only 134mm in height and use 92mm fans.
You can go to the Xigmatek web site and compare the specifications:
ok thanks! now that i saw the diagrams, I understand that the scythe mugen 2 is very good in comparison to other significantly more expensive coolers. So I just dont know wich is better: the ocz vendetta or the mugen 2? because for my socket it is not so significan if I will take the vendetta 2 or the vendetta. thanks!