Is There a Difference Between Inequality and Wealth Disparity?

An article in a journal called ecological economics says economic stratification or ecological strain can independently lead to collapse. And then it says that the new dynamics of this model can also reproduce the irreversible collapses found in history. So in other words, this model has been developed where they can actually go play it back on past times and it accurately predicts the collapses that took place. The rich were just living such an extraordinarily lavish lifestyle, right? A life of complete luxury and they weren't paying any taxes. Then you have all the poor working class that are paying.