First, read who each poem is written by and when; are they all the same gender poets, is it from the same period of history? This will be your first clue as to why their themes may be similar or different.Then, count how many stanzas and what the rhythm of each poem is - asking whether they flow in a similar or different way. What does this mean about the overall feeling that the poem gives?Finally, read the poem. Examine the imagery and emotive language used as well as any techniques which enforce mood and atmosphere.All of these similarities and differences should be marked down, allowing you to see where the poems do/don't stray from one another. This can then become the points you make with evidence in an essay answer.