How Do Different Consensus Mechanisms Achieve Transaction Finality?

Proof-of-Work (PoW) achieves finality through the economic cost of re-mining a longer chain; the longer the chain, the more expensive it is to reverse, leading to probabilistic finality. Proof-of-Stake (PoS) often uses BFT-style consensus mechanisms, where a supermajority of validators must cryptographically attest to a block, granting it deterministic finality.

Hybrid systems may combine elements, using PoW for chain security and a PoS layer for finality assurance.