Butler writes plain, continuous prose throughout. His sentences are long but clear, and his register sits in a Victorian formal middle ground: elevated enough to signal epic, but not stiff. He keeps classical proper names (Achaeans, Jove) without pushing them into archaic territory. Graves writes in rhyming verse for Book 1, which is the most immediately obvious difference: "Inflamed Achilles, Peleus' son / And which, before the tale was done" is metered and rhymed where Butler gives you "the anger of Achilles son of Peleus, that brought countless ills." In Book 6, Graves turns the leaves simile into a four-stanza rhyming poem; Butler keeps it a single flowing sentence. Graves's dialogue in Book 21 reads contemporary and colloquial: "And look at me! Did you ever see so strong or so handsome a man?" Butler prioritises readability and forward movement. He compresses freely, as in the Book 21 passage, where he cuts Achilles' tone down to brisk directness: "the hands of doom and death overshadow me all as surely." He drops connective tissue when it slows things down. Graves leans toward performance and readability over fidelity to the Greek line structure, adding rhyme and stanza form in Book 1 that Homer does not have. The Thetis prophecy in Book 9 becomes a quoted poem within prose, which makes the oracle theatrical but adds framing Homer never uses. Butler loses texture in compression; Graves adds structure the Greek does not contain. A reader who wants the story to move will find Butler easier to sustain; a reader interested in verbal texture and rhetorical shaping will find Graves more varied.
Sing, O goddess, the anger of Achilles son of Peleus, that brought countless ills upon the Achaeans. Many a brave soul did it send hurrying down to Hades, and many a hero did it yield a prey to dogs and vultures, for so were the counsels of Jove fulfilled from the day on which the son of Atreus, king of men, and great Achilles, first fell out with one another.
Sing, Mountain Goddess, sing through me
That anger which most ruinously
Inflamed Achilles, Peleus' son,
And which, before the tale was done,
Had glutted Hell with champions—bold,
Stern spirits by the thousandfold;
Ravens and dogs their corpses ate
For thus did Zeus, who watched their fate,
See his resolve, first taken when
Proud Agamemnon, King of men,
An insult on Achilles cast,
Achieve accomplishment at last.