AI most equal to human player

[SurvivalistMerc]

I'm fairly certain this has been asked before. And maybe I once knew this but forgot the answer....

But I would like to know the exact effects of choosing a specific difficulty for the AI beyond whether the AI will "play better." Specifically, I would like to know if difficulty affects the AI's nation points, resources, or income in any way.

And at what level is the income, resources, nation points, and whatever else is affected (outside "playing better") most equal to what the human player receives?

Thanks