One of these two has put a lot of time and thought into moral questions and is taken seriously by philosophers; the other is a philosophically illiterate know-nothing who pretends otherwise and basically operates on emotion.
For context: Among academic philosophers, John Rawls (A Theory of Justice, 1971) is the most influential political philosopher of the last half century, with fellow Harvard colleague Robert Nozick (Anarchy, State, and Utopia, 1974), in 2nd place. (The most influential political philosopher in that period of time, inside or outside the academy, and in terms of impact on the whole community of American thinkers and not just academics, is probably Ayn Rand (Atlas Shrugged, 1957), self-described "radical for capitalism" but in essential alignment with Nozick's libertarianism on this stuff (individuals' lives are their own and not others' to dispose of, basically).)
In Rawlsian justice, the Difference Principle holds that social and economic inequalities are acceptable if they are of greatest benefit to the least advantaged, among all realistically feasible outcomes. The Difference Principle would be consistent with the most well-off person holding over a billion dollars in wealth as long as the (or a representative) least well-off person or group is better off than they would be under any feasible alternative scenario. Even economic rightists who otherwise tend to reject Rawlsian justice on grounds that it is too egalitarian and/or redistributivist could readily concede that the Difference Principle still allows for this.
Take a society without billionaires -- all societies of centuries ago or numerous countries in sub-Saharan Africa today. Nearly everyone in the society is poor, some extremely poor.
Then take a society that has billionaires -- such as a G7 nation today. Living standards, using all sorts of quality of life measures, are higher pretty much all across the board in comparison/contrast to societies without billionaries; indeed, the relatively least-well-off in a G7 nation may be very much more well-off than a person at (say) the median in the society without billionaires.
By Rawlsian standards, the G7 nation would appear to do a markedly better job than the nations without billionaires of approaching the requirements of the Difference Principle. There's nothing about the inequality in the G7 nation that morally rules out the existence of billionaires as such. This doesn't mean that some G7 citizens still won't have a hard time making ends meet by contrast with the G7 nation's rich; it's just that under the usual economic constraints faced by people, we are dealing with what is feasible: in order to have a society with the living standards seen in G7 countries, there will most likely have to be billionaires. It is hard to believe that any serious student of economics isn't aware of this reality.
So when some know-nothing member of Congress comes along and says that a society that allows for billionaires is morally objectionable, even when the representative least-well-off person in that society is markedly better-off than those of the non-billionaire-having society, and this know-nothing sports an economics degree no less, we might safely conclude that such a person is a moral idiot (and/or that an economics degree means all that much less than it should).
It's like such know-nothings take pride in being ignorant.
(This is without even considering the libertarian/laissez-faire/capitalist alternative to Rawlsian justice as represented by the likes of Nozick and Rand, a position that a know-nothing would not be prepared to argue against intelligently or fairly.)
