Blockchain Infrastructure

What is the difference between Arbitrum and Optimism?

Arbitrum and Optimism are both Ethereum layer-2 networks that use optimistic rollups to process transactions off the main chain and settle them back to Ethereum, cutting fees and raising speed. The main differences are technical. Arbitrum runs its own Arbitrum Virtual Machine and uses multi-round fraud proofs, while Optimism stays closely aligned to Ethereum's execution and uses a single-round proof model. Both assume transactions are valid unless challenged within a dispute window. For users, both lower costs versus Ethereum mainnet; the distinctions matter mostly to developers and at the level of ecosystem and tooling.