The Plan B, taken before the embryo has passed through the one of those tubes in the woman's plumbing, makes the unresponsive to the hormone the blastocyst emits so that it can't attach. It remains an individual. And it remains alive as long as doesn't need to suck life out of someone else. No one has killed it.

RU-486, merely affects the action of the hormones the woman produces, and the result is that the fetus detaches from the woman and liberates itself. It become an independent individual being its life a self reliant individual. No one has killed it.

If a child in Africa dies because you didn't feed it, have you murdered that starving African child?