The difference—and it is major—is that under the Old Covenant, those who trusted God in regard to the Law could not be born again like we are under the New Covenant. Their new birth could not take place until Jesus died for their sins, was raised from the dead and glorified. (See John 7:37-39.)
Before these events happened, another provision was in place. When Old Covenant believers died, they were held or preserved in a place the Bible calls Abraham’s bosom until the work of redemption was completed (Luke 16:19-31). In this sense of the word, they were saved; however, they did not receive the promise of the new birth until after the Messiah paid the price for man’s redemption.
But when Jesus went to the cross, that all changed. Hebrews 10:14 tells us, “For by a single offering He has forever completely cleansed and perfected those who are consecrated and made holy”. Justification, right-standing with God and the new birth are attained only by faith in the blood of Jesus (Romans 3:21-26). They are not attained by keeping the Law because Christ is the end of the Law (Romans 10:4).
After Jesus made the sacrifice for sin conclusively on the cross and was raised from the dead, Ephesians 4:8 states that He ascended on high and “led captivity captive.” This speaks of those Old Covenant believers who were being held in the place called Abraham’s bosom. He took the good news to them that they could receive the benefit of His sacrifice and be born again. They believed the gospel and went from Abraham’s bosom to heaven!
The blood of Jesus not only atoned for our sins; it wiped them out. The Hebrew word atone means “to cover over.” In the Old Covenant, the priesthood covered or atoned for the sins of the Israelites—the breaking of the Law—through the shedding of the blood of animals. The moment we make Jesus our Lord, we enter into a blood-covenant relationship with God. All that the Father has, He turned over to Jesus in the New Covenant (John 16:15). We become joint heirs with Jesus in the new-birth experience (Romans 8:17). God’s riches and best become ours!