What is the difference between these two Kaidos?
One has a two scars instead of 1.
Imagine we read a chapter in the past, Sengoku is talking to new navy recruits. He is discussing about Kaido and says there are only two people existed who gave him a scar. One of them was Fleet Admiral Akainu, who after breaking 30 bones in body from a combine island level Yonkous attack, walked up to Kaido and dealt one blow, before dropping from the pain but was not knocked out.
As fans we would say wow hype for Akainu, but in reality this is was Zoro, no sneak attack. Akainu doesn't even have CoC
and he already dropped in pain but just to whiteboard punch though, he was healthy too, no 30 bones broken.