In Canto 5 of Inferno, Dante descends with Virgil into the Second Circle of Hell. This is where Minos assigns sinners to their particular circle of punishment based on the sins they confess to him.
At this Circle of Hell, Dante encounters those sinners who have confessed to lustful acts generally known as "sins of the flesh." Rather than suffering torture in those parts of their bodies associated with lustful acts or being forced to commit usually hidden sexual acts in public, as might be expected, these sinners are swept helplessly through the air by a tornado-like windstorm and pelted by a ceaseless torrential rain.
This punishment reflects the passions and desires that the lustful sinners couldn't resist or control in their lives, which is what Dante describes as the subjugation of reason by desire. (Inferno 5.38-39).
In Canto 6, Dante wakes to find himself in the Third Circle of Hell with the gluttonous sinners, whose punishment is to lie on the ground and be assailed by a torrential rain similar to the rain in Canto 5, but a rain of sewage, filth, and excrement.
Dante's writing in Canto 5 is lyrical, somewhat distant, and metaphorical. The sinners are borne aloft and swirl through the wind and rain, almost dancelike.
In Canto 6, Dante expresses the Third Circle of Hell in much more prosaic, immediate, and down-to-earth terms. The sinner themselves are condemned to lie on the ground, and their punishment is hurled down on them.
In this circle of Hell, Dante meets a gluttonous sinner named Ciacco, who remarks "if other pain is greater, none is more disgusting" (Inferno 6. 48). Dante's writing style in Canto 6 reflects the disgusting nature of the gluttons' punishment.
In Canto 6, Dante does something which he hasn't done before in Inferno, which is to relate the Third Circle of Hell to a specific location, the city-state of Florence, which Dante calls the "divided city" (Inferno 6. 61).
In this Circle of Hell, Dante also expands the sin of gluttony to encompass the sins of envy, pride, and avarice (Inferno 6. 74-76). Later, in Canto 26, Danto expands gluttony further to include a desire for more and more power and control, which he believes is evidenced in the behavior of the rulers of Florence.
It's interesting to note that Dante wrote Divine Comedy (which includes Inferno) in 1300, just two years before he was exiled from Florence, which was prophesied by Ciacco in Canto 6 (Inferno 6. 64-66)