Apollo
All the planets names are from Roman mythology, not Greek.
Earth
Earth is the only planet whose English name does not derive from Greek/Roman mythology. The name "Earth" is of Germanic origin and comes from Old English and Germanic words meaning "ground" or "soil."
Basically, the only difference was their names, except for Apollo, who had the same name in both Greek and Roman mythology.
Janus, the Roman god of beginnings, transitions, and passages, does not have a direct counterpart in Greek mythology. However, he is sometimes associated with the Greek god Hermes due to their shared roles as guides and protectors of travelers.
In Roman mythology he was known as Mars
Earth. Its name in English comes from Old English and Germanic origins, meaning "ground" or "soil," rather than from Greek or Roman mythology like the other planets.
Out of the old nine, I would say Earth.
Earth (Gaia) is the only planet whose English name does not derive from Greek/Roman mythology. The name derives from Old English and Germanic. There are, of course, many other names for our planet in other languages.
Achilles was a hero from Greek mythology that lead to the victory at the Trojan War, he is the greatest warrior and hero from Homer's epic poem, 'The Iliad'. He is also referred in the Roman mythology, under the same name, since he was a mortal, not a God, Romans only changed the names of the Greek Gods.
Stheno is one of the rare Greek goddesses that did not have a Roman name, only variations of her Greek.
Poseidon. He was named Neptune in Roman mythology. He is not only god of the sea, but god of earthquakes, horses, and hail.