What's the difference?
We have become justified (have become just) to receive the free gift of salvation...
God wanted to make his chosen people jealous...He wanted to offer the Kingdom of God as well as the Kingdom of Heaven to us heathen people...
God knew we could never live up to His laws because His own couldn't do it...So He says, Well I can't even look at sin so somehow I still hafta have a sacrifice...And it's gotta be a blood sacrifice but their blood is no good...
So He says to Jesus, well Son, you're going to have to be the sacrifice to justify this operation...You have to cover their sin, blot it out but it's gonna cost ya...And then God says, after You justify these folks, they can freely ask for salvation...And get it...
That's the difference...