Both of these poems force us to analyse the presentation of the soul in rather unique and fascinating ways. The key similarity between these two poems is the way that the speaker of the soul interrogates it and argues against its sould or advises it. However, the chief difference is in the tone of these two poems and the diction employed.
In Marvell's poem, the animosity between the body and the soul is clear and evident. The body's chief complaint against the soul is the way that the soul forces it to experience the grief of emotions such as fear, love and hope, which are described as being far worse than any physical illness that the body could acquire. Sin is also firmly laid at the door of the soul. As the poem concludes, just as the soul is destroying the body:
So architects do square and hew
Green trees that in the forest grew.
There is something profoundly unnatural therefore about the relationship between the soul and the body, as presented in this poem.
In Shakespeare's sonnet, by contrast, the violence of the language that is present in Marvell's poem is absent here. The speaker merely remarks on the strangeness with which the soul invests so much energy on "Painting thy outward walls so costly gay" when it should be focussing on things eternal rather than the brief beauty that man has before he dies. The speaker thus counsels the soul to be fed "within" and "without be rich no more." Doing this, the speaker says, will enable the soul to defeat death itself:
So shalt thou feed on Death, that feeds on men,
And Death once dead, there's no more dying then.
The tone of this poem, therefore, is very different from the tone of Marvell's poem, and the soul is viewed in terms that are much less violent and destructive. Whilst both poems discuss the relationship between the soul and the body, the dichotomy in Marvell's poem is not nearly so harsh as in the dichotomy of Shakespeare's sonnet.