Genesis 1 and Hesiod’s Theogony are both accounts of how creation came to be. Genesis 1 is, of course, the Hebrew account and the highly credible one. Theogony is the Greek version of the creation of the world. They have very contrast views, Theogony stating that the earth is a god, the sky is a god, and so on.
Genesis 1 recounts like this: ‘In the beginning God created the heaven and the earth.’, continuing with the earth being formless and void. Sequentially in the first six days, God, with the power of his word, created light, divided the waters on earth from the waters in the heavens, formed land; set the sun, moon and stars in space; put birds in the air and fish in the sea, and brought life to the first man. Afterwards, God rests on the seventh day.
Theogony, being a poem, starts out with ‘From the Helicon Muses let us begin to sing,…’, and with a lengthy recounting text tells how first their was Chaos, and Chaos brings forth Night, Gaea (earth), Darkness, and Tartarus. And Night brings forth Strife, Lying Words, Aging, Friendship, Death, Sleep, Blame, etc. Night essentially birthed the dark side of humanity along with Day and Heaven. Gaea and Tartarus’ offspring included Sky, Mountains, the Sea and storms. Gaea birthed also the Titans which included Cronos, Iapetus, Oceanus, Hyperion, etc. Gaea (after a part of this tale which won’t be recounted here) encouraged her sons to dismember their father with a sickle she crafted. All declined except Cronos, who followed through with her plan. Ironically, Zeus, Cronos’ son, enacted the same deed upon his father.
In the above paragraph one can see that in Theogony, there is a vicious revenge cycle told and that the gods are neither perfect, nor omnipotent. The gods procreate more gods, some being the source of man’s imperfections. This is the difference between Genesis 1 and Theogony: in Genesis, one all-powerful, all-seeing, invisible, perfect God speaks the universe into existence. He crafts a utopian world unblemished. Later in Genesis is the story of how man brings all the sin and death into the world. In Theogony, all the evils exist even before man exists. The gods themselves are imperfect and have physical bodies that can be injured and even killed.
Conclusively, Genesis 1 is a vastly more practical recounting of the beginning of time than Theogony, its perspective being that gods exist in large quantities, gods make more gods, gods injure other gods, etc.