They are not a million miles apart. 2 out of an infinite number of variations of a policy. Major UBI plans will likely involve major changes to the tax system a

They are not a million miles apart. 2 out of an infinite number of variations of a policy. Major UBI plans will likely involve major changes to the tax system anyway, either as part of the initial legislation or eventually and the net effect of either could be very similar. So, it's mostly a semantic difference. But, going off the two scenarios you mention the UBI version has a little more of what makes the idea appealing to the political right (though there have been negative income tax ideas that came from the right too). The main one being losing the complexity, overhead, unintended consequences, perverse incentives and nannying that comes with means testing. I think there are arguments to be made for either.