How Does Transaction Finality Differ between Various Consensus Mechanisms?

Transaction finality is the guarantee that a transaction cannot be reversed once confirmed. In PoW (like Bitcoin), finality is probabilistic; it increases with each confirmation but is never absolute, hence the risk of 51% attacks.

In many PoS systems (like Tendermint or Ethereum's Casper), finality is deterministic after a certain number of validator votes, meaning the transaction is cryptographically guaranteed to be irreversible after that point.