There should not be any difference in content between the itch and Steam versions. The Steam version just has Steam integration features like Steam achievements.
Viewing post in A Dream of Burning Sand comments
Thanks for the quick response Eldwood, I've been playing the game a whole bunch on steam since then! I have one other question if you will allow it... Is there any hint you might give regarding legitimately reaching the 'you will die' boss area? Should I re-read books for clues? I've tried falling down all sorts of paths, killing the red eyed ghosts, running the fire area in a loop, playing at midnight, etc, I'm at a loss... (I even gave up and used the level select to find the entrance in reverse, but still can't find a way to open it up properly... hmmm)
Anyway, probably will take a break after this playthrough, think I'm on track for the best ending at long last <3 Just wanted to uncover as many secrets as I could before moving on... Every time I thought I knew everything, I stumbled onto a brand new secret. And it's been great fun :)