As stated above, the first paragraph will discuss the themes and how they compare and contrast. As for comparisons, the themes from "The Bean Eaters" and "Mirror" remotely resemble each other. Respectively, the themes were "poverty and old age often leave people with only memories" and "beauty changes with time." The key idea that makes these similar is 'old.' When you get older, your beauty changes. And the other theme explains itself. The other two poems "Fifteen" and "A Blessing" have themes that don't resemble each other or either of the other poems. The theme of the former is "at the brink of adulthood, younger people are often torn between childhood fantasies and adult realities"; that of the latter is dealing with feeling at one with nature. So the poems have both comparing and contrasting themes.
These poems also have speakers that can be compared. In "Fifteen" the speaker was a boy older than 15 years; in "A Blessing" the speaker was approximately the same age. In "Mirror" the speaker was a mirror; in "The Bean Eaters" it was the author. So in both cases, the speaker is not a person in the story. However the speakers of the first pair do not compare with the speakers in the second pair of poems. So in the case of speaker, these poems also compare and contrast.
These four poems -- "Fifteen," "The Bean Eaters," "A Blessing," and "Mirror" -- all had themes and speakers. These could be both compared and contrasted. Some themes were similar; some weren't. The same goes for speakers. In conclusion, one can see that two seemingly different poems can have similar elements, or different elements. It just depends on the poems.