There is a difference. Does Big Mom always use Napoleon? Does Whitebeard always use his Bisento? No right?
Haki mastery over your primary weapon IS the fundamental difference. I dont expect Mihawk to be able to punch mountains with his monstrous haki. I expect him to slice it and then some.
This is why I say Shanks and Mihawk are incomparible as of now. It comes down to whether or not you believe Shanks fights with more than just his sword, and I personally do. We will never see eye to eye on this unless you accept that as a possibility
There is no difference between Shanks and Mihawk, lol. Dont bring Big Mom and Whitebeard to help you, they cant.
What haki mastery? Mihawk is better than Shanks in Haki, lol. If you dont expect Mihawk to punch mountains with his monstrous haki why are you expecting that from someone who has worse haki than Mihawk?
I still dont see any reasons why you would say Shanks>Mihawk except for personal power scaling which has nothing to do with manga...
Incomparable? Too bad for you but Oda has made them comparable since always, even tipped the scale in Mihawk's favor.
You can believe that Shanks fights with whatever you want, fact is, none of those things make him superior than when he is with a sword.
Until you accept that fact, we indeed will never see eye to eye. Acting as if something is superior to a sword... lol