Aldarc
Legend
@EzekielRaiden talks a bit about it in the thread that he links earlier. Not to steal his thunder, but he gets to the heart of it there: the big difference is that healing surges are a pacing mechanic in 4e. Healing surges capped healing abilities, and they were also used to power some magic items and rituals.Sorry to be obtuse, but you can explain that a bit more? How are hit dice and healing surges very different, or evince very different approaches to game design?
So imagine if we were playing D&D 5e and the cleric casts Healing Word on you. What happens? The cleric player rolls 1d4 + their character's spellcasting modifier. If we were playing D&D 4e and the cleric casts Healing Word, the other player would (optionally) spend one of their healing surges and gain an additional 1d6 HP. Your healing surges were not based on how many HD your character had, but, rather, were determined by class: e.g., Cleric (7 + Con modifier per day), Fighter (9 + Con modifier per day), Wizard (6 + Con modifier per day), etc. So effectively, healing surges were both a pacing mechanic and a way for healing to be relative to the target's total HP value.