Two structural differences
Polymarket and Betfair work the same way on the surface. Underneath, two things are built differently: where your orders are recorded, and who holds your money. Everything else follows from these two.
Public vs private
Polymarket records every order on a public blockchain, open for anyone to read and verify. Betfair keeps its order book on private servers only it can see.
Non-custodial vs custodial
On Polymarket your funds stay in a wallet you control. On Betfair the platform holds your balance and gives it back when you withdraw.
Betfair records orders privately.
Polymarket records them publicly.
Both work the same way on the surface. You take a side, set your price, and trade the probabilities. The structural difference is where the orders are recorded. Betfair keeps its order book on private servers that only Betfair can see. Polymarket settles every trade on a public blockchain, so the full record is open for anyone to read and verify.
Held on Betfair's servers. The market price is visible; the individual orders behind it are not.
Each trade is a public record: the wallet, the side, the amount, the price.
A concrete example: a trader who says they won $1M on Betfair can't be verified, because the record sits on Betfair's private servers. On Polymarket, the same claim is tied to a wallet on a public ledger, so anyone can go and check it for themselves.
This is what makes Traderline Sonar possible
Because every Polymarket order lives on a public ledger, Sonar can show you the whole market: the biggest holders, who is actually profitable, and every move the moment it happens.
Explore SonarBetfair custodies your money.
Polymarket is non-custodial.
This is the second structural difference. On Betfair you deposit funds into an account Betfair controls. The platform custodies your balance and pays your returns back to you. Polymarket is non-custodial: your funds stay in a wallet you control, and the platform never takes possession of them. One practical consequence: if an account is put under review, on Betfair the balance is tied up with it; on Polymarket the account and the money are separate, so the funds aren't held by the platform in the first place.
- Funds are held in the platform's account
- Returns are paid back to you on settlement
- The platform can freeze or limit the balance
- Funds stay in a wallet you control
- Returns settle straight to your wallet, no withdrawal request
- The platform never takes possession of your funds
Non-custodial means control sits with the user, not the platform, which also means the responsibility does too. Whoever holds the wallet keys holds the funds, so securing them is the user's job, not the platform's.
What it comes down to
Strip away the detail and it is one question: who holds your money, and who carries the security.
- Full control of your wallet
- No blocks, no limits, no freezes
- The security is yours to keep
- Your money sits at the platform's disposal
- The platform controls it and can block or limit access
- The security burden is theirs, not yours