I have noticed some differences in the Lego Star Wars figures. This post points out the difference between the Chewbacca figures.
I have two Chewbacca Lego figures in my collection. The earliest comes from the Imperial AT-ST set, released in 2001. The serial number for this set is 7127. The second Chewie figure comes from the Limited Edition X-Wing Fighter set, released in 2006.
|AT-ST set 7127|
|X-Win set 6212|
|Chewbaccas: 7127 set (right) & 6212 set (left)|
So keep your eyes peeled fellow Lego Star Wars enthusiasts!