Of course there's a difference. In NIT you literally get less money as you make more money. UBI you don't. No people do not consider UBI a disincentive to work and it's the major argument for UBI.
Not all startups are by people like you and me. Sometimes there are people who poor and trapped in a scarcity mindset and whose economic thinking is governed by fear. Those people could never reach their full potential. UBI really helps.
Would a entrepreneur with a startup aspiration really drop it to become poor and be entitled for NIT?