Condemnation is either from Satan or our sinful hearts. Conviction is a gift from the Holy Spirit.
Condemnation causes us to turn away from God in fear, dread, and shame. Conviction causes us to come to God and freshly place our faith in the perfect life and death of Christ.
Condemnation causes us to wallow in despair and self-pity. Conviction leads to God-centered hope.
Condemnation leads us to believe that we’ll never change. Conviction gives us hope that, even though we sinned, God is still at work in us.
Condemnation is inward, self-focused, and always dwelling on the fact that I have sinned. Conviction is outward, God-focused, and always dwelling on the fact that I have sinned against God.
Condemnation sees God as an angry judge who could strike at any moment. Conviction sees God as a loving Father who disciplines his children.
Condemnation can actually cause us to forget repentance because we are so inwardly focused. Conviction leads to quick (but not hasty) repentance.
Condemnation feels like a black, oppressive cloud. Conviction feels like a sweet, though often very painful, interaction with the Lord.
Condemnation is useless and sinful. Conviction is fruitful and pleasing to the Lord.
I could not have said it better myself (and always need to be reminded of these truths)
From: Stephen Altrogge at The Blazing Center » The Difference Between Condemnation and Conviction