the only changes ive noticed is that you barely get damaged when you run into doors

Slower hunger and sleep drain, longer days, easier daily tasks, although day duration has its own setting now.

To clarify, "easier daily tasks" means that you'll have to gather fewer hash codes from satellites per day.  I believe you only need to grab one per day on the lowest difficulty.  It may also cause servers to go down slower/less frequently, but don't quote me on that.
With the way difficulties are set up, the lower difficulties basically make the game slower.  On a higher difficulty, you'll have to manage your time carefully, between aggressive hunger and stamina drainage, many satellite hash codes, and still sending in your daily signals and fixing downed servers.  However, this means that the game won't offer any less to players on lower difficulties.  As long as you're in the story mode, you'll experience the same thing at every difficulty,  just at a varying pace.  It isn't like there are any particular game mechanics that get either added or entirely omitted exclusively for casual players.  It's quite good game design, actually.