Liquid collateral: While BNT stakers are issued Staked BNT when they lock their tokens in the staking contract, those tokens are just a representation of their staked position and are not yield-generating on their own. In contrast, xBNTa is a liquid, fee-earning asset that can be transferred from wallet to wallet, added to liquidity pools or deposited as collateral for loans. (xToken Lending coming in Q2.)