Originally Posted by
stampdog316
Mark II is the newest version just released in Jan 10, Prime remix is the older rules, now commonly called Mk I.
There has been literally thousands of posts on the differences but the biggest change is MK II streamlined the rules and uses icons to symbolize weapon abilities traits. This also cuts down on the amount of text on the cards. They also corrected imbalances of some of the models by improving some and weakening others. Warjacks are more powerful now and and you get free points from your caster for them so they are more viable.
As for the rules--line of sight is now different, unit and formatioin rules are simplified, advance deployment is now 6" instead of 12, warjacks can spend focus to shake off stationary effects or stand up, you can now charge through rough terrain-- there are more differences but these are the bigger ones coming off the top of my head.