In Constantine P. Cavafy's poem "An Old Man", strongly depicted what an old, retired, boring old man's life is like. An old man can never find something fun to do, he's always tired and bored, wanting to go back to childhood again, but all is too late and lost. This is what Cavafy wants to communicate to us, he tries to tell us how miserable and boring an old man can be.
In the meanwhile, Czeslaw Milosz's poetry is the somewhat an antithesis to Cavafy's poem. Milosz's poem is somewhat more optimistic then Cavafy's work; while Cavafy talks about how life is miserable when you are nothing but an old man, Milosz talks about life in a child-like point of view, where life and the world is al full of excitement, full of imagination, full of spaces for exploration.
There's one more point that makes two of them antithesis to each other, in many of Milosz's works, it often shows much doxologies in them, many of God-loving, God-praising evidences can be easily found in them.
And in Cavafy's works, it's totally opposite, he talks about life mean meaningless when it comes to an end, it reminds me of existentialism.
There's many obvious opposite characteristic in both, one is more optimistic, and the other is more pessimistic. But we can be sure that both of them have the grand cycle in them.