In the OT times a man had his sins forgiven through the Levitical system God set up for the nation of Israel. Their sins were forgiven but not forgotten. Their sins were forgiven but not cleared.
Exodus 34
6 And the Lord passed by before him, and proclaimed, The Lord, The Lord God, merciful and gracious, longsuffering, and abundant in goodness and truth,
7 Keeping mercy for thousands, forgiving iniquity and transgression and sin, and that will by no means clear the guilty; visiting the iniquity of the fathers upon the children, and upon the children's children, unto the third and to the fourth generation.
Under the NT, man's sins are forgiven and taken away, washed with the blood of Jesus Christ, never to be remembered.
Hebrews 10
4 For it is not possible that the blood of bulls and of goats should take away sins.
17 And their sins and iniquities will I remember no more.