1- King and Katakuri are around the same age: King is 47 years old, Katakuri is 48 years old.
2- Both of them are the First Commanders of their respective Yonko crew and the right hand men of their captains.
3- They wear the same manner of dark black edgy spiked leather clothes.
4- They say the same line in the anime:
5- They both have an over 1 billion bounty.
6- Both of them hide/cover their faces and get angry when someone sees it.
7- They have the same crimson red eye color.
8- Both of them have tattoos on their bodies.
9- Both of them have a calm, collected and stoic personality, preferring to talk less.
10- Finally, both of them end up fighting the 2 strongest in the Straw Hats crew who have Conqueror’s Haki (Luffy & Zoro respectively) in 1v1.
*by centurion