There is a difference between removing something with the intent of removing it, and it dying in the process (even if you knew that was inevitable) and killing something with the goal to kill it.

We have laws like this all over the place, especially in self defense. If you shoot your attacker, you are in the clear, even if they die and you knew their death was inevitable. But if you shoot your attacker, and the court finds out that you have a previous relationship with that attacker and openly wanted him dead, you will have a much harder time defending yourself in court. It's legal to use lethal force in self defense, but it's illegal to abuse a self defense situation in order to kill someone. Even if the situations are the same, it is a determination of the court.

With abortion, and with the medical procedures we have at this time where there is no reasonable way to remove the fetus immediately without its death, I believe that the law should be that you have the right to remove the fetus, even if it results in its inevitable death, but you do not have the right to kill the fetus for the sake of killing it.

In practice, this would be the difference between a woman getting an abortion because she doesn't want something in her body and a woman getting an abortion because she "doesn't want a child now." It's a subtle difference, but a very important difference. Yes, it will be difficult/impossible to actually enforce. But so are the self defense laws. This type of law would essentially just give a legal path for particularly extreme cases.