The Iliad, is a written account of the final weeks of The Trojan War with Achilles as the protagonist. The Odyssey is Odysseus' ten year journey from Troy after the Trojan War to his homeland Greece....
It is uncertain who really wrote the two epic poems, but it is most commonly believed to have been a blind man named Homer. However, some say it was more likely a woman
I'm not sure if you mean which was written first or which came first in the story. The Iliad came before the Odyssey because the Iliad is the story of the Trojan War whilst the Odyssey is the tale of...