If you go to this page link and click on the third news item "More details on FoG V2.0" you can see the list of changes.
In summary:
Skirmishers less slippery, with reduced ability to slow enemy movement and less ability to concentrate shooting without risk.
Drilled troops less manoeuvrable and undrilled troops less unmanoeuvrable.
Very large ("swarm") armies easier to break.
Commanders limited in how many battle groups they can command as a battle line – making Field Commanders more worthwhile.
Interpenetration anomalies prevented.
Elephants improved.
Close combat effects of superior armour reduced.
Changes to rules for rear support and routing make historical multi-line formations more viable.
Ability of high quality troops to keep fighting despite heavy losses reduced.
Steve