In comparing Achilles and Aeneas as a hero, explain the difference and similarities of their motivations.
Both men are great warriors, but with completely different motives and characteristics. Aeneas has been charged with a divine mission: to found the city of Rome. He must therefore be prepared to undergo a dangerous, arduous journey that will test his physical and mental strength to the absolute limit. But Aeneas is only human, and, like any human, has myriad foibles and character flaws. He falls hopelessly in love with Dido, queen of Carthage. This temporarily diverts him from his mission. However, after a swift intervention from the gods, he comes to his senses and continues with his journey. Aeneas loves Dido, but as a true progenitor of the Roman warrior male, he must do his duty no matter what.
Achilles, on the other hand, is only half human, and it shows. There's something godlike about him; he's in a class apart from mere mortals. He's an incredibly brave warrior, the best of the Achaeans, but his bravery borders at times on recklessness, without heed for the consequences.
Whereas Aeneas is motivated by a desire to bring glory to future generations of Romans, Achilles is always looking out for number one. He has no qualms whatsoever about sulking in his tent like a grounded teenager after King Agamemnon requisitions his sex slave. No matter much Agamemnon tries to appease him, no matter how many of his comrades are slaughtered in battle, Achilles simply will not budge. It's only when his close friend Patroclus is slain in battle by Hector that he returns to the fray. Even then, he will only fight to heal his own injured pride and to restore the honor of his name.
Achilles, the son of mortal Peleus and the goddess Thetis, is the focal point of Homer's Iliad. The name of Aeneas, the son of mortal Anchises and the goddess Venus, can be found in the title of Virgil's epic poem, the Aeneid. Although Virgil was influenced heavily by Homer, Virgil gives his hero different motivations.
Achilles is motivated by individual glory. Prophecy has told him that he can die young and glorious at Troy, or live to a ripe old age at home in Greece.
Aeneas is motivated by a national glory that awaits for the Roman race that he will help to found. After surviving the Trojan War, Aeneas sets out in search of a new homeland, a homeland that various prophecies have told him will be in Italy. Establishing that new home is the focus of most of what Aeneas does.
Achilles, in contrast, does not have to establish a new homeland or reclaim a homeland that has been lost. Achilles fights for glory and also fights, in the Iliad, to avenge the death of his comrade Patroclus at the hands of the Trojan Hector.
Aeneas has his own instance of vengeance. His ally Pallas was killed by Turnus and Aeneas, in the closing lines of the poem, avenges Pallas' death by killing Turnus.
As we can see, Achilles and Aeneas do share some similarities, but Achilles' quest for glory is an individual one, whereas Aeneas is more of a "team player". His motivation is the establishment of a nation whose glory will reach its height hundreds of years after his own death.