Easy difficulty: Enemies aren't too aggressive, bosses attacks can be parried, bosses aren't as aggressive and don't deal 2/3rds of your health in one attack
Medium (normal) difficulty: Everything does normal amount of damage
Souls like (hard) difficulty: Enemies are very aggressive and will follow you, bosses can deal 2/3rds of your health in a single hit, bosses cannot be parried, and bullshit may occur