poseidon

As proper nouns the difference between poseidon and hera

is that poseidon is poseidon while hera is hera, the queen of the gods, the goddess of marriage and birth, and the patroness of women.

As a proper noun poseidon

is poseidon.

As an adjective undefined is

lacking a definition or value.

As proper nouns the difference between poseidon and cthulhu

is that poseidon is the god of the sea and other waters, earthquakes and horses while Cthulhu is a gigantic fictional humanoid alien god being described with a head resembling an octopus and dragon wings and claws, around whom an insane cult developed.

As an adjective Cthulhu is

pertaining to the mythos of Cthulhu and additional otherworldly beings created by H. P. Lovecraft or inspired by his writings and imitators.

In greek god terms the difference between pontus and poseidon

is that pontus is a god of the sea while poseidon is the god of the sea and other waters, earthquakes and horses.