What Is the Difference between a 51% Attack on a PoW versus a PoS Blockchain?

In a Proof-of-Work (PoW) system, a 51% attack requires controlling the majority of the network's mining hash power, which is resource-intensive and requires significant capital expenditure on hardware and energy. In a Proof-of-Stake (PoS) system, a 51% attack requires controlling the majority of the staked tokens.

While both allow for transaction manipulation, the PoS attack is generally considered an "economic" attack where the attacker's own stake is at risk of being "slashed," providing a stronger economic disincentive.