How Does a “Validity Proof” Differ from a “Fraud Proof” in the Context of Blockchain Finality?

A validity proof (used by ZK-Rollups) is a cryptographic proof submitted with the transaction batch, demonstrating that the new state is correct before it is accepted by L1. A fraud proof (used by Optimistic Rollups) is a mechanism submitted after a state root is posted, challenging its validity and proving that the state transition was incorrect.

Validity proofs ensure finality immediately, while fraud proofs only resolve finality after a challenge period.