"And for this cause he is the mediator of the new testament, that by means of death, for the redemption of the transgressions that were under the first testament, they which are called might receive the promise of the eternal inheritance. For where a testament is, there must also of necessity the death of the testator. For a testament is of force after men are dead: otherwise it is of no strength at all while the testator liveth." (Heb. 9:15-17).
The new testament did not go into effect until the death of the testator. Jesus Christ. While He lived, the old testament was in effect. He came not to destroy the law, but to fulfill it, remember?
There’s life in the blood until the lamb was killed. The life is taken out from the mortal Old lamb. Not the eternal lamb( JESUS) which is everlasting so its always there. So the opposite of the old lamb is the life giving blood of Christ because he lives on for eternity. That’s the difference.