Look them up in the dictionary. That's what those words mean to me.
Here's a definition for you.
Universal basic income definition
A basic income (also called basic income guarantee, Citizen's Income, unconditional basic income, universal basic income (UBI), or universal demogrant[2]) is a form of social security[3] in which all citizens or residents of a country receive a regular, unconditional sum of money, either from a government or some other public institution, ...
Can't find welfare anywhere in the definition, so as you requested I will stand by the dictionary definition.