Gini Coefficient measures the inequality among address balances. Calculated as a square measure above the Lorenz curve. The closer the curve to the straight line, the less the Gini coefficient. If all balances were equal, it would be exactly 0. For the most uneven distribution, it is 1.
Nakamoto index is the number of top addresses, holding togerther more than 51% of all coin supply. Measures the prevalence of top balances comparing to whole population. 90%, 99%, 99.9% indexes are how many addresses together hold 90%, 99%, 99.9% of total supply respectively