The only major change that I can recall is to the Combat Sequence, otherwise it's pretty much just a rearranging of the material.
The combat sequence had a Fire Phase(B) and a Fire Result Phase (B) added.
They also changed missile attacks from taking 75% activity to only taking 50% activity.
You might find this article of interest:
http://www.icewebring.com/what-is-rolemaster/