Thunderbrd
C2C War Dog
One is a religious motivation and usually more personal, an exchange of life-essence currency for favor. This is not necessarily a highly publicized act as it is for the favor of the one doing the sacrificing, or his often very private and limited organization, more public in ancient times perhaps.Et tu, TB?
Okay here's capital punishment. "Society" (by which I of course mean a tiny privileged minority far more criminal than those they condemn) decides that it cannot protect itself from these people without killing them.
Human sacrifice of the unwilling was to thank a (monstrous) god for victory by donating some of the spoils to him (both sides considered people could be property so no difference there).
In both cases, "society" decides it will benefit from the deaths of these people. Wrong decision? Probably. But I honestly don't believe it is wronger in either case.
The other is a punishment and a threat to others to never ever do what this person has done to earn such a fate. Always as public as possible so as to spread far and wide the fear of challenging the laws that were broken.
Often, the human sacrifice is secretive and would be considered highly deviant in the society it's taking place in, though again, in ancient times some cults that practiced it became widely accepted by the culture, but then even in those cases, it rarely had anything to do with what the people who were being sacrificed did to deserve the fate, though yes sometimes it was because they were slaves or rivals or had acted out in some way but that wasn't necessary at all. They might have even been selected because they had done everything right in life so far and were thus pure - such as virgins of age.
Capital punishment is almost always an act reserved for the most heinous of crimes and decisions that can be made. It is a fate threatened to the public but earned by the choices of the individual coupled with an inability to avoid the promised response to those choices.
I see them very differently. Perhaps the most telling difference is that committing human sacrifice in modern society is likely to earn you capital punishment.