  Odysseus of the Iliad foreshadows Odysseus of the Odyssey not only in his epithets (resourceful, long-suffering, etc. ) but in his whole character. I do not know whether this means that the same man composed both Iliad and Odyssey; but it does mean that the author of the Odyssey thoroughly understood the Odysseus of the Iliad.
We can, I think, argue from one work to the other. Odysseus is crafty, resourceful, daring, and merciless. These characteristics have usually been taken as essentials of his personality, from which stem the stop-at-nothing politician of Sophocles, or Dante's treacherous captain ( Inferno , Canto 26). But guile and unscrupulousness are only secondary characteristics of the Homeric Odysseus. Essentially, he can be described by the Greek word sophron (though the word is not Homeric). This is untranslatable. It means, not necessarily that you have superior brains, but that you make maximum use of whatever brains you have got. Odysseus is the antithesis of Achilleus. Achilleus has a fine intelligence, but passion clouds it; Odysseus has strong passions, but his intelligence keeps them under control. Achilleus, Hektor, and Agamemnon, magnificent as they are, are flawed with uncertainty and can act on confused motives; Odysseus never. So those three are tragic heroes, but Odysseus, less magnificent but a complete man, is the hero of his own romantic comedy, the Return of Odysseus , or Odyssey . A single purpose guides Odysseus in the Iliad. The expedition against Troy must succeed. Whether this motive grows out of personal affection for Agamemnon is not clear.
But this is the end toward which the demoralized army must be rallied, Thersites chastised, Achilleus propitiated, Agamemnon braced. A single purpose guides Odysseus through the Odyssey as well. He must get home and put his house and kingdom in order. To do this, he must drive his men and himself, outwit and outlast trial by danger and trial by pleasure, leave the blandishing goddesses, fight down his joy at seeing home and wife for fear joy might give him away prematurely, fight down, for the same reason, rage at seeing the disorder in his household.
A man who could win through all this is a man supremely adequate, in mind and body; therefore, by corollary, resourceful, much enduring. Odysseus can be most eloquent, but he wastes no eloquence on Thersites--who has an unanswerable argument--but beats him up and makes him cry, which is far more effective.
He can build a raft and sail it, or build a bed, or plough a field. He has no recklessness, but does have stark courage when that is needed; the Odysseus who makes the plans for others to fight by is post-Homeric. Always equal to the occasion, he startles the Trojans who think he looks like a fool and can be no orator, as he startles the suitors who take him for a broken-down tramp. Not the noblest or stateliest of Homer's heroes, he is the one who survives. 
