EDIT: Let’s cool it with the downvotes, dudes. We’re not out to cut funding to your black hole detection chamber or revoke the degrees of chiropractors just because a couple of us don’t believe in it, okay? Chill out, participate with the prompt and continue with having a nice day. I’m sure almost everybody has something to add.
I think it’s more accurate to say it’s a combination of both. Some brains are equally powerful overall but differently specialized. There’s also different levels of specialization via education and experience. Two people can have similar skillsets with one being more specialized than the other.
But there’s also things like brain injuries, malfunctions, and breakdowns that can reduce overall capability. With these, it’s possible to be worse at everything without anything you’re better at.