Flamestrike
Legend
Punching with a padded glove is a far different situation than being hit by an axe, arrow, or bullet.
IMO the difference between the wizard and the barbarian would be 10-15%, tops. A barbarian would be harder to hit, though.
Thats what HP represent. Dodging ability. And Parry skill. And using armor and shields better than other people. And Skill. And Resolve. And Luck. And the Will to Live. And Heath.
A 1st level Wizard PC with 8 HP who gets 'hit' by a Frost Giants axe and takes 30 damage, is narrated as him zigging when he should have zagged, the axe hitting him square, and being cut in half.
A 20th level Barbarian PC who gets 'hit' by a Frost Giants axe and takes 30 damage, is narrated as leaping out of the way at the last second, as the shock of the 1 tonne axe slams into the ground next to him, coming up in a fighting stance, ready to counterattack.
In your modern game, a 1st level PC with 5 HP who is 'hit' for 30 damage from a machine gun burst is turned into a pink mist as he charges directly into the beaten zone of the MG. The 20th level PC standing right next to him who takes the exact same 'damage' is narrated as leaping into cover at the last second, the bullets landing around him and whizzing overhead, before leopard crawling to a firing position, ready for his next bounding move.
Audie Murphy had 200 Hit points:
The Germans scored a direct hit on an M10 tank destroyer, setting it alight, forcing the crew to abandon it. Murphy ordered his men to retreat to positions in the woods, remaining alone at his post, shooting his M1 carbine and directing artillery fire via his field radio while the Germans aimed fire directly at his position. Murphy mounted the abandoned, burning tank destroyer and began firing its .50 caliber machine gun at the advancing Germans, killing a squad crawling through a ditch towards him. For an hour, Murphy stood on the flaming tank destroyer returning German fire from foot soldiers and advancing tanks, killing or wounding 50 Germans. He sustained a leg wound during his stand, and stopped only after he ran out of ammunition. Murphy rejoined his men, disregarding his own injury, and led them back to repel the Germans.