Basic Income and UBI are colloquially synonyms, people use them interchangeably, and the Irish government are almost certainly using it to endear themselves to supporters of UBI and to get more coverage for their policy than media would give them if they just called it a grant.

This happens all the time. For example, in the UK there was a push for a "living wage" in the 2010s, which the government responded to by rebranding the minimum wage the "National Living Wage" and bumping it a little for over-25s.

This seems to be the same thing.

The first word of UBI is universal. The entire concept relies on that characteristic.