Multi-sig is another type of Bitcoin P2SH script that uses the OP_CHECKMULTISIG op code. The difference between OP_CHECKDATASIG and multi-signature wallets is that the second party does not need to agree on how and when the BCH is sent. The oracle (which can be the seller, buyer, or arbitrator) doesn’t have the ability to place conditions on the transaction.
With a multi-signature transaction, not only must both parties agree on exactly how the BCH is spent, but both parties must be online at the same time to sign the transaction. This is because both parties must sign the full transaction including all outputs and inputs. With a Script that uses OP_CHECKDATASIG instead, the oracle simply needs to give the winner a signature, which they can use at any time to unlock the BCH in any way they choose.