I'd say that the point of the Gospels isn't eternal life (especially not in the sense of manufactured immortality that the Miracle brought about), but salvation. So there isn't a difference, Jack's blood brings salvation - the freeing breath that goes around the world - just as much as Christ's blood does, through death. Christ's death, but also the transformation of death in itself is a big point in Christianity, and necessary for the real life.

I really like that, because the absence of death in MD can hardly be called 'real' life. Somehow it always comes back to mortality defining what it means to be human...