these arent even the same chopper, but different models entirely. Its more than a simple refinement.
the rear fuselage boom has a slab sided cross section on the upper pic and a rounded one on the lower pic, this points to a completely different
design and structure. making further comparisons (fin against fin, cockpit door against cockpit door etc) shows that there is virtually no similarirty
at all, other than a cursory similarity in overall form. 
external image
Furthermore, if the first image in the thread is related to either of them it can only have been as a quick and cheap design excersise or mechanical testbed as it too is completely different in detail design and could not be 'modified' to the standard of either design shown here.

