What you’re identifying falls under viability as mentioned above, as well as basic independent self-regulation.
They’re not the same life, because they’re two different things: one is a premature newborn that we know can survive outside of a continuing pregnancy, and the other is a fetus that might survive. Unless you propose that we make all pregnant people deliver the moment their doctor believes that the fetus is viable (that seems like a bad state of affairs?), the two will remain different.
That makes no sense. A 26 week old premature baby that is born is still at a high risk of death. We don't know if it will survive. Yet we give it the full protection of any human being, but if one hour ago it was in the womb, we don't.
They’re not the same life, because they’re two different things: one is a premature newborn that we know can survive outside of a continuing pregnancy, and the other is a fetus that might survive. Unless you propose that we make all pregnant people deliver the moment their doctor believes that the fetus is viable (that seems like a bad state of affairs?), the two will remain different.