No, I really don't think you can say one aspect over another. True, positional play requires little to no calculation, BUT, GM's can often squeeze out wins from the tiniest edges, and that's often against tough defense (though probably with some very subtle mistakes... in amateur play the defense often cracks very badly at some point), and I don't think any amateur player can come close to that with any consistency.
So, roughly of course, they're equally superior at both, though in my case I would probably get hammered in tactics because that's where I'm weaker.
I think GMs live for chess...so yes, they would be better than all the rest of us in tactical and positional play...but I think it runs way beyond this. Their experience puts them on another level where we can't reach...unless we sacrifice ourselves as they do. Most GMs are only beaten by other GMs.