My friend Edward Mendelson, teacher extraordinaire, has made a little chart about symmetries in the Iliad. You can do this with the Odyssey as well — oppositional or echoing events seems to have been a major feature of Homeric composition. For instance: 

Odyssey chart.

By experiencing the journey of Telemachus away from home, and then the nostos of Odysseus, we see different ways of life to which we compare and contrast life at home on Ithaka. As Odysseus says (in Robert Fagles’s translation), “Nothing is as sweet as a man’s own country, / his own parents, even though he’s settled down / in some luxurious house, off in a foreign land / and far from those who bore him.”