Why both chains talk about parallel execution
Most older chains execute transactions one after another, so throughput is limited by a single core. Sui and Sei both start from the observation that most transactions do not touch the same state and can run at the same time. They just reach that goal from opposite sides: Sui redesigned the data model and the language, Sei kept the Ethereum developer stack and parallelised the virtual machine underneath it.
Sui: objects instead of accounts
Sui, built by Mysten Labs, does not model state as accounts with balances. Everything is an object with a unique ID and an owner: a coin, an NFT, a game item, a pool. Objects are either owned by one address or shared between many. Transactions declare which objects they touch, so the scheduler knows immediately which ones can run in parallel.
The distinction has a second effect. A transaction that only uses owned objects, such as a simple transfer, does not need the network to agree on an order relative to everything else and can be finalised on a fast path. Transactions on shared objects, such as a DEX swap, go through full consensus. That consensus is Mysticeti, a DAG-based protocol that replaced the earlier Narwhal and Bullshark design and brought finality to well under a second for ordered transactions.
Contracts are written in Sui Move, a dialect of Move with the object model built in; assets are first-class values that a contract bug cannot silently duplicate or drop. Fees are paid in SUI. Validators set a reference gas price each epoch, and part of every fee is a storage charge that is refunded when the data is deleted.
Sei: Cosmos base, parallel EVM
Sei launched its mainnet in 2023 as a Cosmos SDK chain with a built-in order-matching module and a Tendermint-derived consensus tuned for speed. That consensus is called Twin-Turbo: blocks are propagated optimistically and processed before they are formally finalised, cutting block times below the Cosmos norm.
The bigger change was Sei v2 in 2024, which added an EVM that executes transactions in parallel. Developers deploy ordinary Solidity contracts; the chain detects conflicting transactions and reorders them, and non-conflicting ones run concurrently. A custom storage layer, SeiDB, was added to keep state access from becoming the bottleneck. In 2025 the team announced a further redesign, Sei Giga, aimed at much higher throughput with a new consensus; treat it as announced and verify what has shipped.
Because of this history Sei has two address formats for the same key: a native bech32 address starting with sei1 and a 0x address for the EVM side. They are linked once you use both. Fees are paid in SEI on either side.
Side by side
| Sui | Sei | |
|---|---|---|
| Virtual machine | Move VM, object model | EVM, parallelised, plus Cosmos modules |
| Consensus | Mysticeti (DAG-based) | Twin-Turbo (Tendermint-derived) |
| Fee token | SUI | SEI |
| Address format | 0x plus 64 hex characters | sei1 (native) and 0x (EVM) |
| Typical wallets | Slush (formerly Sui Wallet), Suiet | MetaMask via EVM, Compass, Keplr |
| Developer stack | Move, Sui SDKs | Solidity, standard EVM tooling |
| Signature of the design | Fast path for owned objects | Ethereum compatibility at high speed |
What each is used for
Sui's ecosystem leans on features that only its model makes easy: sponsored transactions, where an app pays gas for its users; zkLogin, which lets a user control an address through a Google-style login without a seed phrase; on-chain game assets; and a storage network from the same team, Walrus. DeFi exists but is not the only story.
Sei's ecosystem is what you would expect from a fast EVM: DEXes, perpetuals, lending and games already written in Solidity. Its argument to developers is that nothing needs to be rewritten.
Address gotchas
Sui addresses start with 0x, exactly like Ethereum addresses, but they are 32 bytes long, not 20, and Sui is not EVM-compatible. A MetaMask address pasted into a Sui payout field is invalid, and a Sui address pasted into an EVM field is invalid. If your Sui wallet shows an address and it is much longer than an Ethereum one, that is expected.
On Sei the opposite confusion happens: a 0x Sei address looks like any EVM address, and it is one, but only on Sei. Funds sent to that address on Ethereum or Arbitrum are on those chains, not on Sei.
Risks specific to these chains
- Validator concentration. Both chains run delegated proof of stake with a limited active set. In May 2025, after the largest Sui DEX was exploited, validators coordinated to freeze the attacker's addresses. That shows the set can act quickly, and also that a small group can decide what moves.
- Foundation and investor unlocks. Both projects were venture-funded and have multi-year vesting schedules for teams, investors and foundations. Unlocks are public; read the schedule before holding a large position.
- Young execution layers. Parallel engines are newer code than the sequential ones they replace; bugs can surface in the scheduler, not only in contracts.
- Roadmap versus mainnet. Anything not yet on mainnet is a plan.
Which one to choose
If you want Move-style asset safety, app-sponsored gas or login without a seed phrase, Sui. If you want to use tools you already know from Ethereum on a faster chain, Sei.
From a swapping point of view the difference is simpler. SUI is a core asset here with its own coin page and a direct SUI to SOL pair, and it is available in the swap form in both directions. SEI is not in the swap form at the moment.
Swapping SUI without an account
- Open SUI to SOL or pick SUI in the swap form.
- Enter the amount and your Solana address as the destination.
- Click Swap now, copy the SUI deposit address from the status page and send exactly the shown amount.
- The floating rate locks when the deposit is confirmed; SOL is paid out to your address with the network fee already built into the quote.
To go the other way, buy SOL first from USDT TRC-20 to SOL, or pick SUI directly in the swap form from any listed asset. Keep a little SUI in the receiving wallet for future gas.
SUI → SOL
USDT (TRC-20) → SOL