How do the Definitive Edition difficulties map to the HD difficulties?

I'm loving DE so far, but I'm having a hard time understanding how the AI difficulties compare to HD's AI difficulties.

I keep seeing people say that the Definitive Edition has better AI, but the game seems ridiculously easy now. I haven't really played in two years, but I'm sailing through modes/difficulties that I used to struggle with on the HD version.

Anyone know the details on how these two games stack up against each other?