Buy Now Pay Later (BNPL) is a service to allow users to buy NFTs over a 3-month period. After making a downpayment, users will make payments every 31 days until the very last payment. There is no need to worry about margining.
Pawn is a collateralised loan against a user's NFT. Cyan will appraise the NFT, and loan the user up to 1/3 of the value for 3-months. A user can borrow ETH for 20% or 33% of the NFT's appraisal for 3-months, or 50% of the appraisal for 24-hours.
Vaults are for ETH stakers. ETH staked in the Vaults are used to fund the BNPL and Pawn plans on the Cyan protocol. Interest paid back on the plans go straight to the Vault, with the underlying NFT as collateral. If there are plan defaults, the Vault becomes the owner of the NFT, which is liquidated.