How does the Chaucer's attitude toward the Monk differ, if at all, from his attitude toward the Friar?
First, it is not always possible to infer the author's attitude from the persona of the poetic speaker, or narrator. In this case, however, it is fairly well agreed that the ironic and observant poetic narrator is giving voice to Chaucer's satirical comment upon society. Chaucer's narrator has nothing very favorable to say about either the Monk or the Friar, thus has a poor attitude toward them, though he criticizes them for different reasons.
The attitude conveyed toward the Monk is satirical, critical, and ironic. The narrator is criticizing the Monk for being caught up in the luxurious lifestyle as though he were a lord of a manor instead of a prelate (i.e., clergyman of high rank) in the Christian Church--at the time, the European Christian Church was the Roman Catholic Church (the first Latin/Greek Church Schism had occurred in 1054). The Monk is identified as one who loves "venery," which may be both love of hunting and love of sexual impurity. This criticism confirms that the Monk delights in worldly luxuries and pleasures instead of the rules of his religious Order.
rules he thought were old and rather strict,
...let old things pass away 175
So that the modern world might have its day.
That text he valued less than a plucked hen
Which says that hunters are not holy men,
The attitude conveyed toward the Friar is the same satirical criticism and irony but for different reasons. The narrator criticizes the Friar for being greedy and presuming to sell forgiveness. The Friar is a member of a humble begging religious order and purchased exclusive begging rights to his begging territory. He also holds a license to "shrive" (i.e., hear the confessions of and absolve sins) anyone he comes across. The friar is noted for the fact that if tears of sincere repentance could not be made forthcoming, an ample gift made to him would nicely insure the sincerity of the repentance. In other words, he was selling absolution (i.e., cleansing and forgiveness) from sin for the cost of a gift of wealth, like silver, to himself.
He'd sweetly listen to confession, then
As pleasantly absolve one of his sin.
He easily gave penance when he knew
Some nice gift he'd receive when he was through.
If someone gave, the Friar made it clear,
He knew the man's repentance was sincere.
Instead of tears and prayers, they might therefore
Give silver ....