I’m always confused between Mackinac and Mackinaw. As I understand it, Mackinac is the island north of the town of Mackinaw. However, when I visited in-laws in Petoskey, they kept pronouncing the island “Mackinaw”.
I don’t think anyone really makes a distinction unless they’re going to one specific place.
It is one of those things that makes Michiganderians smile with disdain, especially when someone pronounces it with a hard C.
It’s pronounced Mackinaw even when it’s spelled Mackinac.
Both words are a contraction of “Michilimackinac”, generally thought to be the Ojibwa term for “Great Turtle”. “Mackinaw” is English; “Mackinac” is French. They are pronounced the same.