Angles. It's all about angles. The heart lung area on a turkey is pretty small. On a boradside shot it's best to aim for the butt of the wing so that the bird can't fly. Frontal shot aim just above the base of the beard. Slight angled toward you aim in between.

It's also recommended to get less penetration than with deer sized game and keep the arrow in the bird to help immobilize them. That probably means a lot less bow poundage and a BIG broadhead. Some even say a large mechanical with some sort of stopper behind it so you don't blow through.

I would guess that the base of the neck would pretty much take them out, too.