How's Hard AI

I've been constantly winning Moderate AI since I bought the game not long ago (although I always try to do early rushes to kill off some of his workers to slightly undermine his economy. Not sure how bad I damage him, he always manages to tech up faster than me).

Now I'm considering to step up to Hard AI and I'd like to get some spoilers and the taste of things to come. How different is Moderate AI vs Hard? Anyone made some research and observations?

Thanks in advance.