Here are several of the characteristics of Dante's levels.
1. Shape: The levels are ring-shaped or circles. Within some of the circles on the outside (the 8th circle for example) are even smaller divisions so that people guilty of the same type of sin such as fraud can be separated by the extent of their sin (i.e., Was it intended to hurt others? Did it lead people astray spiritually?).
2. Numbering: The numbering of the circles progresses from smaller to larger: the worse the sinner, the larger the number. Characters and historical figures found in the outer rings such 1 and 2 have not been found guilty of terribly malicious sins such as those who dwell in Circles 8 and 9.
3. Inhabitants: Dante interestingly chooses to depict historical figures in the various rings to demonstrate how their earthly lives were actually perceived in God's eyes and to illustrate that not all sin is the same. Thus, betrayers like Julius Iscariot and Brutus and Cassius spend eternity in the worst and innermost circle because from Dante's interpretation, they are guilty of the worst type of sin. Dante does take opportunity to criticize the hypocrisy of politicians and religious leaders by portraying them as inhabitants of hell rather than paradise.