These poems at first appear quite dissimilar in theme and style. Thematically, however, there are certainly points of comparison to be made, but it is easier to approach this essay by breaking down each element separately.
Looking at the element of style first, we might consider the following points:
1. "Married Love" is written in free verse, having neither a rhyme scheme nor a strict rhythm or meter. By contrast, "I Heard A Fly Buzz" is written in a regular meter and features examples of both pure rhyme and pararhyme (or assonance) on the second and fourth lines of each stanza. "Married Love" has three stanzas of differing lengths, while "I Heard A Fly Buzz" has four of equal length.
2. There are, however, some points of comparison, despite these marked differences. Both poems are written in the first person, from the perspective of, probably, a woman (although not necessarily so, in the case of Dickinson's poem). Furthermore, both poets impose their personal stylistic touches upon their poems; in Rosenberg's case, the use of free verse marks a departure from the typical constraints of poetry; in Dickinson's case, we see the distinctive use of long dashes, which guide the reader's breathing and represent a diversion from typical poetic structures of the time.
In terms of theme, some points to consider:
1. On the face of it, the two poems are very different thematically as well. The theme of Dickinson's poem is death and the moment of death, the idea of "stillness" at the moment of death and the irritation of having that stillness interrupted by something—in her case, a fly buzzing. The fly interposes itself "between the light" and the speaker, making itself more important even than the "King" the speaker hopes to witness "in the Room," such that all she can perceive is its "uncertain stumbling buzz."
2. The theme of Rosenberg's poem is "married love," or rather, the fear that she will "go sliding down beneath" her husband soon, because the "easy brotherly lust of marriage" is no longer sexually satisfying to the poet. If Dickinson's theme is death, Rosenberg's is love and the humdrum way it sometimes comes to fit into our lives.
3. However, on closer inspection, we can see that there is a common theme between the two poems. Dickinson's poem returns over and over to the fly; the speaker cannot stop thinking about it and focusing on it, making it difficult to argue that the poem is truly about death at all. Likewise, Rosenberg's poem is called "Married Love," but the "throb" to which the speaker continually returns is what actually dominates the poem. This "throb" expresses itself in a series of sexual images, featuring "some man" and "the gas attendant," rather than the speaker's husband. Sexual longing and list is identified as a "smolder," and the words "burned" and "burning" reinforce this association. The thread continues between stanzas, as in the final stanza, the speaker imagines herself as a "burning ship," the "throb" of lust becoming a distraction and an irritation—just as the fly is an irritation to Dickinson's speaker in the moment of death. In both poems, then, the secondary theme of the speakers' distraction and irritation almost overrides the superficial themes of death and marriage, pulling the speakers away from their stated points of focus.