structure an answer

You can compare two poems based on language techniques and the content such as theme. First, start by analysing each poem separately. Background, context, themes, title come under content while language techniques range from rhythm, rhymes, alliteration, assonance, onomatopoeia and so on. When you analyse you look for the effect created by the language technique so, for example, alliteration and the purpose of using alliteration at a certain point. Look for connections between these techniques and themes, background, context and content. Once you are done analysing each poem you look for the similarities and differences between both poems in terms of all the features such as content and literary devices.
Then you can structure your essay. An example of a common structure would be:
Introduction: 1 paragraph on introducing and outline of the essay
BODY: Similarities talk about the similarities between the two poems, You can use one paragraph per feature let`s say both poems were written during a similar time period you discuss that in one paragraph and move onto the next paragraph on similarities of other features between the poems
BODY: Differences now talk about the differences between the two poems. Again you can use one paragraph to talk about one feature that is different between both poems and proceed to the next one.
CONCLUSION: summarize what you have mentioned throughout and end with a conclusive statement.