The Crimson Binome
Hero
As the 5E rulebook is keen to point out, different people describe HP damage in different ways. It's not at all uncommon for a given DM to say that "crit = head shot" on a consistent basis, just like it's not uncommon for a DM to say that 8 damage is 8 damage regardless of whether your max is 5 or 50. The system is only as abstract as you make it, and there's no requirement for you to interpret it one way or another. Some people like to read it as more directly informative than is strictly required.If you equate 'head shot' with 'critical hit', you don't fully understand the D&D combat system. A critical hit in 3e or later editions indicates an unusually good hit, but it still in no way specifies the outcome in any fashion. It could still just be a scratch on the arm. We don't actually know until the DM applies hit points to the target.
[...]
Maybe. Nothing prevents a critical hit from an axe only doing 3 damage (normal strength, minimum damage). The normal person with 4 hit points might be severely lacerated, but he's not dead. And the normal person with 2 hit points, might be dying, but not necessarily dead. In either case, the color of the outcome need not be 'head shot'. The only time 'head shot' can be equated with critical hit is when the target is a helpless foe and the player colors his proposition with, "I hit him in the head."
In a 3E game, critical hits with a battle axe for a total of 3 damage are not something that the system is designed around. In that game, the major use-cases of battle axe attacks are made by someone with a Strength of at least 14. The rules do exist to cover that situation, but even if you're following the (extremely common) guidelines I've put forth here, the fact that it doesn't exactly line up with our pre-conceptions about reality is not something that is likely to stand out during the game. Even if some random peasant does get a critical hit with an axe - which is already unlikely, given the amount of screen time is spent on random peasants - the damage is much more likely to be 14 rather than 3, and 14 damage is enough to kill any normal orc or goblin.