Compare and contrast the themes of Andrew Marvell's "To His Coy Mistress" and Christopher Marlowe's "The Passionate Shepherd, To His Love."
The two poems you ask about share the same theme. They are both, in effect, carpe diem (Latin for "seize the day") poems, though "Shepard" is not the classic, traditional carpe diem poem that "Mistress" is.
The speaker in "Mistress" and the shepard of the second poem are trying to talk their lovers into something. The speaker wants his lover to make love with him now instead of waiting, and the shepard wants his lover to come live with him in the country and, presumably, do the same thing. The emphasis in "Shepard" isn't on time (right now) like it is in "Mistress," but he still wants his lover or would-be lover to seize the day and come share bliss with him.
"Mistress," though, is what we today call a metaphysical poem. It is somewhat of an intellectual game of words, featuring, among other things, stretched metaphors such as "vegetable love."
"Shepard" is a pastoral poem. It features the beauty and treasures of rural, "pastoral" life.
Though the speakers of both poems are trying to talk their lovers or would-be lovers into something, they do it in different ways.