Battle field differences are plenty! All enemy unit +30% to atk + Def makes a huge difference, as does +4 global morale boost means routing the enemy is much harder. it's equivalent to the morlae boost granted by and 8 command general!

Combine with less starting cash limiting your expansion development and military funds in the early game, while AI can expand more quickly/fund a bigger military/tech up faster.

I don't think it was any impact on things like alliances etc. or effectiveness of subterfuge units.