Rifster is correct on the mushrooms although I don't know the actual amount of food they give you.

The only differences I've noticed on normal and hard from the easy game is in the generic gameplay.

More diseases, more injuries, tougher to impregnate the women. Tech research seems to go slower. Villagers loose interest quickly and don't want to work, and it usually takes many tries when training someone for them to actually clue in.

Although the puzzles are all the same, it just seems to be that you have to watch them much more carefully and often.

If anyone picked up on any other differences, let us all know because I'm curious too.