As far as the eSky Lama and the CX/2 are concerned, there are only a few parts that are interchangeable...

1. The outer shaft and main gear are identical.
2. The bottom gear is identical, but the inner shaft is different. So, if you swapped a Lama's inner shaft witha CX/2's , you would have to use the CX/2's blades. But, then your upper and lower blades wouldn't match, and you would have to get the CX/2 lower rotor head and blades. The inner shafts are the exact same length, but the upper rotor head has slightly different spacing than the CX/2. Also, the kinkage on the flybar is just a little bit shorter on the Lama than the CX/2 and so is the flybar (just by a very small amount). It also has a slightly different ball-connecter which is smaller too. So, you would have to do some slight modification to interchange these parts...
3. The motors are identical even though they are mounted in different locations.
4. All bearings and mounting collars (including top collar).

Other than that, that is pretty much it. It is actually quite a bit of work to interchange parts between these two helis, but it can be done for some things very simply. I hope this helps...