Arbitrum vs OP Mainnet

Arbitrum One and Nova are optimistic rollups using Nitro fraud proofs that compress transactions into calldata submitted to Ethereum. The Orbit toolkit lets projects deploy their own Arbitrum Orbit chains with configurable permissions. ARB token governance manages the 3 000‑plus validator whitelist and a 1 billion‑dollar ecosystem grant fund.

OP Mainnet (Optimism) is an optimistic rollup that batches transactions to Ethereum and relies on fraud proofs submitted during a seven‑day challenge window. The Bedrock upgrade in 2023 cut L1 calldata costs by 40 % and introduced multi‑proof modularity. ‘RetroPGF’ rounds redistribute protocol revenue to public‑goods builders, governed by the OP token‑holder Collective.