Moderate campaign difficulty

So I beat every mission on standard difficulty but I dont want to stop playing the game (single player only for me) and want to try going for moderate difficulty. So how does the difficulty change? I know that some missions are difficult even on standard. How do the missions change?

depends a lot on the scenario/mission. sometimes enemies start with more units/produce more units, sometimes you start with less units or less techs.
I think the wiki might include more details