A punch can break macro structures like veins, and making you skin blue. But most of the cells survive it.
A burn will instead kill all the cells that got above 60celsius. So the whole area is dead, 100% dead. There is no survived cell that can help the surroundings. Your dead tissue will simply stay there and rot. There is not even a blood vessel remaining to bring blood with nutrient, antibodies etc to heal the wound.
Latest Answers