Action Length, Twist Rate, etc.
For ballistic differences, kind of like .308 vs 30-06. Not much of a difference, small enough to be meaningless to some folks.
You have a couple things to consider.
1) Like .308 vs 30-06, your shorter cartridge, the 260, is suited to shorter actions. The Swede NEEDS a long action.
2) Factory loads - it doesn't sound like you're stuck with one or the other there, since you commented about brass, so never mind that one.
3) Rifle itself - there are surplus Swedes to be had, and their actions are among the very smoothest of any Mauser ever made. No surplus 260s, of course.
4) Twist rate - remember, the Winchester .243 beat the living hell out of the .244 Remington because its faster twist could deal with heavier bullets. Same thing to watch here. If you want to shoot heavier animals with it, like the Swedes do for moose (yes, moose), you will want the faster twist for the heavier bullets.
I'd be happy with either, and I think you will be, too. I have a 96 Swede in its original issue condition, and it's a joy to shoot.