Size of skill gap between each AI difficulty?

I only have a disc of TT without online so I play against AI bots. I've been playing moderate because I'm far from a master at the game. I know that easy doesn't pick up relics and only uses a few soldiers in pushes, and is very inefficient at playing overall. I also know that moderate actually uses most of the game's mechanics, but can be locked in a loop of just sitting there and/or doing the same puny push over and over. I wanna know how higher difficulties work so I can judge whether or not I can move up easily.

How hard is hard, how much more so than moderate? Same question for titan in comparison to hard? What does each difficulty make use of or do that lower difficulties generally don't?