The answer depends on the specific mythology you're referencing. In Greek mythology, Helios is primarily considered the god of the sun, though Apollo is also associated with light and, at times, conflated with Helios.
Helios: The Original Sun God
Helios was the original Greek sun god, often depicted driving a chariot across the sky each day. He was responsible for bringing light to the world and was a powerful figure in the Greek pantheon.
Apollo: God of Light and More
Apollo, while not solely the god of the sun, was associated with light, knowledge, healing, music, and prophecy. His connection to light sometimes led to an overlap with Helios's role, and in later traditions, Apollo was sometimes seen as a sun god.
Roman Mythology: Sol Invictus
The Romans equated Helios with Sol. Later, a cult of Sol Invictus ("Unconquered Sun") gained popularity in the Roman Empire.
Sun Goddesses
It's also important to note that many cultures have sun goddesses, showcasing the diversity of solar deities across different mythologies.
In conclusion, while Helios is primarily recognized as the Greek god of the sun, Apollo also shares associations with light. The Romans worshipped Sol, and later Sol Invictus. Other cultures may have sun goddesses.