The use of unit cards is the biggest difference in deployment. In 2nd edition, you place unit cards face down in your deployment zone, as does your opponent. Each unit card represents a unit, an individual, or a false lead. All the relevant info for the models can be written on the back of the card, making things easier to consult. Between the false leads, and by positioning your forces to maximize their capabilities and the terrain on the board, tactics become elevated. The models come on the board in the second turn when they activate, and it's a wild system. I don't think any other game has that.
The Dark Axes were FAQ'ed down to 32 points, but in general, all the units were reconfigured and balanced. I'm going by my experience playing every army in 2nd edition, and they all are effective when played to their strengths and the dice go your way. I haven't played first edition, and there are some out there who prefer it, but the general consensus has been that 2nd edition smoothed out the balance so every army was viable.
Some still play the first edition, and I agree, the cover art was unbelievable!!
Either way, we all love the setting and the armies that make up Chronopia.