Setting the Advantage - what does it change?

[Benedict151]

Apologies in advance if this is documented somewhere but I have searched and not found it.

From reading the forums it seems that for solitaire play setting the advantage between +20 and +40 for solitaire play is recommended but does this actually change?

E.g. if I set it at +20 for the AI does it give it bigger units (20% "more stuff"?), better units (increase their attributes by 'x' amount?), make it more effective in combat (its firing more lethal or tougher defence values?). Maybe it gives it another advantage or a combination of any or all of these? Or does it apply to the players units - e.g. units 20% smaller etc? 

The reason I ask is I only really play solo (I know I should play H2H but for various reasons I generally prefer not to) and I'd like to have some understanding of what altering this value does before embarking on my next big game.

Many thanks for any information

Ben