Walt Whitman and William Carlos Williams are both noted for their mastery of free verse. However, the two poets are quite different in the ways they use their freedom. William Carlos Williams seems almost to be creating new forms, with rules that he determines himself. "Spring and All" falls neatly into two parts, with thirteen and fourteen lines respectively. The second half is structured like an inverted Shakespearean sonnet, with the couplet at the beginning. Williams maintains tight control, varying the number of syllables in a line slightly but maintaining an average of approximately eight, as in the standard iambic tetrameter of English verse:

But now the stark dignity of
entrance—Still, the profound change
has come upon them: rooted, they
grip down and begin to awaken

Whitman's approach in Leaves of Grass is very different, with long, sprawling lines for his long, sprawling epic. Where Williams pares his poetry down to the essentials, Whitman delights in pleonasm and repetition:

My tongue, every atom of my blood, form'd from this soil, this
air,
Born here of parents born here from parents the same, and their
parents the same,
I, now thirty-seven years old in perfect health begin,
Hoping to cease not till death.

How do Whitman and Williams approach poetic form in Leaves of Grass and Spring and All?

Walt Whitman and William Carlos Williams’s approaches to poetic form in Leaves of Grass and Spring and All are comparable in terms of how their excitement shapes the length of the line and whether to use free verse or prose.

In Spring and All, Williams switches from prose blocks to free verse. In a sense, Williams’s form in Spring and All is a product of his belief that he doesn’t need to stick with either lyric poetry or prose poems (or just flat-out prose paragraphs). As Williams declares before the Samuel Butler section, “The imagination, freed from the handcuffs of art, takes the lead!” The poetic form derives from Williams's exuberant viewpoint that his imagination and creativity should guide the shape of the poems in the collection.

Whitman brings a similar ebullience to the poetic form in Leaves of Grass. Whitman’s euphoria manifests in his long lines. Sometimes, his poetic line goes on for so long that they extend to the next line and have to be indented to demonstrate to the reader that, no, this line is still a part of the previous line. Like the form in Spring and All, Whitman’s form can be messy and unruly, as both poets appear palpably excited by the possibilities of new, dynamic forms. For example, in “A Song of Joys,” Whitman exclaims, "O to make the most jubilant song! / Full of music—full of manhood, womanhood, infancy!”