The art of war 3 unlimited mana hack basically generates unlimited mana (cash) for you so that you can buy any units without worrying about spending cash on buying more mana.
Now the art of war 3 mana hack generates a larger amount of mana (cash) for you so that you can buy any units without worrying about spending cash on buying more mana. So it's much better than unlimited mana as it gives much higher amounts of cash to be spent.