If you're familiar with hymns, you'll know they're usually written in rhyming quatrains and have a regular metrical pattern. Dickinson's quatrains (four-line stanzas) aren't perfectly rhymed, but they sure do follow a regular metrical pattern. We'll show you what we mean.
Iambic meter is supposed to follow the most common pattern of English speech, so if you didn't notice that this poem was written in meter, don't worry about it! That just means Dickinson pulled it off without it sounding forced. The first and third line in every stanza is made up of eight syllables, or four feet. A foot is made up of one unstressed and one stressed syllable. So the first line, if you were to exaggerate it, might sound like this:
Be-cause | I could | not stop | for Death,
The vertical lines mark the feet. Since there are four ("tetra") feet per line, this is called iambic tetrameter. The second and fourth lines of each stanza are in the same iambic metrical pattern, but because they have fewer syllables (and therefore only three feet) it's called iambic trimeter (tri = three).
The important thing to know is that there is a regular pattern here, even if Dickinson, rebel that she is, breaks it a couple of times. Can you find where?
The rhyme isn't regular (meaning it doesn't follow a particular pattern) but there is rhyme in this poem. "Me" rhymes with "Immortality" and, farther down the poem, with "Civility" and, finally, "Eternity." Scattering this same rhyme unevenly throughout the poem really ties the sound of poem together. Also, "Chill" and "Tulle" are half or slant rhymes, meaning they sound really close to a perfect rhyme but there's something a little off.
Another thing that ties the poem together is the repeated phrase, "We passed," which is changed a bit in the fifth stanza to, "We paused." This repetition of a word or phrase throughout a poem is called anaphora and it's a technique poets use a lot in order to help the poem progress as a well as tie it together.
You probably noticed that Dickinson likes to capitalize nouns, but what is the effect? Capitalization can make the words seem more important; it certainly stands out, and it can also slow the reader down a little, making us pause to consider the word rather than breezing through the poem. Those dashes have a similar effect sometimes. They both make us pause and usher us on to the next line. You might think of them as connecters or strings, pulling you through the poem.