What the difficulty settings do?

[Southern Hunter]

I was playing on 'Napoleon' level, and found my lines being outshot by columns, even sometimes when facing away from me!

Sleeping on it, I wonder if the difficulty levels affect tactical combat with some modifiers?

Is there a difficulty level that leaves tactical combat 'fair', but makes the strategic elements more difficult (less money, unhappier enemies, etc) ?

I presume the difficulty levels go from - Less difficult through standard to very difficult, and then the 'named leader' levels are more difficult again? Or are they some parallel system to the 'very difficult' system?

Hunter