The major difference between the poet Dante and the character or pilgrim Dante is that the author is less sympathetic to the sinners in the circles of Hell than is the character. The poet Dante obviously wrote the Inferno; he created the circles of Hell, determining which sins were the "worst" and which symbolic punishments would be paired with each sin. Dante chooses to punish the traitors in the ninth circle, the worst of the worst being eaten for eternity in the three mouths of Satan. His personal biases are on display, as well. For example, in the Vestibule of Hell, Dante harshly punishes the "opportunists," who did not choose a side in political conflicts or the corps of angels that did not choose a side between God and Satan when the latter rebelled. This comes from Dante's distaste for political bandwagonners; Dante himself was exiled for his loyalty to a group that was no longer in power. These sinners in the Vestibule are not even deemed worthy of a place in Hell, but nor can they hope of the redemption that Purgatory can bring. Those in Hell feel superior to the opportunists because they, at least, sinned deliberately and accept their symbolic punishment accordingly.
The pilgrim Dante is a weaker and more sensitive character than the poet who created the Inferno. Dante is seen fainting at the end of some of the cantos and describes his fear and anxiety throughout the poem. Also, Dante's character is more sympathetic to the sinners in Hell, whereas the poet Dante is the one who put them in Hell to begin with. A good example of this occurs in Canto V when Dante speaks to the doomed lover Francesca. She was damned to Circle Two of Hell, where those who committed sins of the flesh are punished by being whipped around in an eternal whirlwind. Dante hears her account of how she and her lover were drawn together and how her husband walked in on them and killed them both before they ever had a chance to confess their sin. Dante feels pity for Francesca, but it seems Dante the poet does not, as he has chosen to punish her here in Circle Two.
The distinction between Dante the poet and Dante the pilgrim character is related to Dante's overall purpose in the Inferno. If he wants to appeal to the reader and have them reconsider their lifestyles and get back on the path to salvation, he has to make his character relatable. If Dante the poet were simply to preach at his reader, it would be difficult to win the reader over. On the other hand, depicting the character version of himself as a weak sinner who needs and wants to get back on the path to heaven allows Dante to capture the reader's trust and attention.