I do think it worth noting that while hit points have always been somewhat variable as to specific interpretation (ie. where are you hurt), they have also always been primarily linked to actual physical wounds, albeit in a general, non-maiming (and slightly unrealistic way). (So no one rests a hand back on, but nobody loses their hands either short of vorpal weapons or nasty traps and DM say-so, but if they do lose a hand, regeneration can put it back on.)
I dispute the "always", at least as a generalisation. Perhaps "always" for some, but not "always" for everybody.
In his DMG (p 61), Gygax explains that "hit points are not actually a measure of physical damage, by and large, as far as characters (and some other creatures) are concerned" and hence "the location of hits and the type of damage caused are not germane to them". (By "type of damage" Gygax doesn't mean cold vs fire vs piercing, but rather types of injury such as "sprains, breaks, and dislocations": p 61, 1st paragraph.)
This is reiterated down the page - "Damage scored to characters or certain monsters is actually not substantially physical - a mere nick or scratch . . . it is a matter of wearing away the endurance, the luck, the magical protections" - and comes up again on pp 81 and 111, where he says that "The so called damage is the expenditure of favor from deities, luck, skill, and perhaps a scratch" and that "the accumulation of hit points . . . represents the aid supplied by supernatural forces."
Gygax also links this, on the same page, to the range of decision-making options the game provides: "Combat is a common pursuit in the vast majority of adventures, and the participants in the campaign [ie the players] deserve a chance to exercise intelligent choice during such confrontations. As hit points dwindle they can opt to break off the encounter and attempt to flee. With complex combat systems which . . . feature hit location, special damage, and so on, either this option is severely limited or the rules are highly slanted towards favoring the player characters".
The thought is that a genuine system of
injuries would eliminate this choice, because a player whose character was injured would not be able to have his/her PC escape combat even if s/he wanted to (due to the physical impediments suffered by the character).
I know that not everyone played hit points in accordance with the quotes I've provided, but it was an interpretation of hit points that was extent at least from 1979 (when the DMG was published), and it expressly
denies any link between hit point loss and actual physical injury, "until the last handful of hit points are considered". This is the interpretation of hit points that 4e draws upon and develops.
There ar two main differences, as I see it, in 4e compared to AD&D run with mojo hit points. First, rather than focusing on "the last handful of hit points" as the locus of physical injury, focuses on the resolution of the "dying" state and death saving throws to determine whether the blow that led to zero hit points was a serious physical wound (that killed) or not (a mere swoon from which the character recovers). This is also manifested in the fact that a 4e character who recovers from 0 hp is back at full capacity (like Frodo after being "stabbed" by the troll) whereas in 1st ed AD&D that character is physically debilitated until s/he rests or receives magical healing beyond mere hit point restoration. (In the DMG this is a
heal spell; Unearthed Arcana added the
death's door spell.) I believe that both AD&D 2nd ed and 3E retained the AD&D 1st ed notion that losing the last handful of hp signals serious physical injury, while doing away with the recovery requirements for regaining consciousness; to me this is a move towards the sort of theoritecal incoherence that [MENTION=6790260]EzekielRaiden[/MENTION] describes, which - as [MENTION=6775031]Saelorn[/MENTION] has described - is resolved in practice by virtually all recovery being magical.
Second, 4e doesn't emphasise retreat and pursuit in the ways that Gygax's AD&D does. Rather, the decision points in 4e, which are facilitated by an absence of a mechanical "death spiral" resulting from treating hit point loss as genuine physical injury, are about (i) the unlocking of healing surges during combat, and (ii) the deployment of rationed action resources (attacks, moves, etc).
Cure Light Wounds, et.al. all refer to "wounds" which refers to the fact the character has been wounded.
They also refer to wounds that are "light", "serious" and "critical", although as is well known a Cure Light Wound will restore
to full health the typical human who has suffered any injury short of one that causes death or unconsciousness, while Cure Critical Wounds will not restore to full health a Conanesque hero who has taken a few scratches and bruises that are manifestly well short of a critical wound.
Hence why some of us regard those spell labels as being less than literal in their meaning.
A third difference in 4e from AD&D is it's adoption of fully proportional healing, but while I'm a big fan I think this is more of a technical tweak than a significant gameplay departure from Gygaxian AD&D, when compared to the first two differences that I mentioned.
It's probably also worth noting that 4e does retain some legacy terminology from AD&D: hit point recovery is still called "healing", "regeneration" etc although it is not literally that. The "dying" state is given that label, although - if the character is revived - then it turns out s/he was never actually dying at all (so "dying" is really a metagame label -
there is a chance, by the game rules, that this character will die - rather than an ingame label). The cleric's surgeless healing dailies are called Cure X Wounds (depending on how many surges worth of healing they permit).
These might be the sorts of legacy things that [MENTION=85870]innerdude[/MENTION] had in mind in the edited post upthread. Being mere labels, they don't both me. (Any more than, playing AD&D, I fussed very much about the healing spell names.)