In principle? Not sure what that means, but the incentives of a negative income tax vs. a UBI are different and that's why a UBI is preferable.
Is the incentive to work different? I thought it worked like this:
Under UBI if you earn $1 you are always $1 richer. Under negative income tax, if you earn under some threshold, when you earn $1 you are < $1 richer because the govt will hand you less.