*edit* Wow, I typed slow.. got beat twice. Ah well, I'll leave the info anyway.
Kinda sorta.
Depends on what you mean by "overall damage".
A slug will hit hardest, and leave the biggest hole, but its only one shot. One shot from any gun can kill anyone, its all about placement. But sure, being hit in a non vital location with a 12 gauge slug is going to suck 15x worse than being hit in the same spot with say, a 9mm round. A slug will, however, sail through walls of a home. So that defeats the purpose.
Buck shot is big balls, think along the lines of store bought sling shot ammo. That would be somewhat less "powerful" than a single slug, but being multiple projectiles, it will make it more likely that you will hit the target, as well as leaving several holes in said target. It would be like being shot 9 times with a small caliber hand gun all at the same time. This inflicts massive and very deadly damage. Chances to hit and chance to hit something vital are multiplied by 9. (assuming 9 ball bucks shot, there are a gagillion different sizes) These will also sail through a wall. Which is why I keep bird shot first, cripple, move in, kill if needed.
Bird shot, although considered less deadly that the other two, (and certainly less deadly at longer range) inflicts horrifying damage at close range (aka in home gun fights). Hundreds of little tiny lead balls shread things at very close range. Shot across a living room (20 feet), a robber will be brought down by a retarded amount of pain. think of having 1000 dull needles stab you through the chest, neck, and face at one time, penetrating 1-3" deep. Its a surgeon's nightmare because he'll spend 5 hours digging around in your flesh and checking every hole for critical damage. If you live, you could get lead poisoning and die anyway. Also, those little balls like to get into arteries and kill you 2 days later when they lodge in your brain or trigger a heart attack. at very close range, say 8' or less it will just obliterate whatever you point it at. We're talking arms and legs being blown off, Heads going missing.. Messy to say the least.
I'd say the slug would be least deadly, in comparison to the other two. Buck shot being the most deadly.