I wanted to map ' to " because I think both ` and ' does the same thing. But I don't want to shadow anything without knowing properly. So, any differences between ` and '?
' jumps to the start of a line where the mark is set, whereas ` jumps directly to the specific character.
Personally, I find that I use ' far more frequently than `, in part because it's easier to reach, but mostly because it means I don't have to care (or try to remember) precisely where within the line I set marks.