The planet that is closer to the Sun between Earth and Mars is Earth.
To understand why, we need to look at their positions in the solar system. The average distance of the Earth from the Sun is about 93 million miles (150 million kilometers). In contrast, Mars is further away, with an average distance of approximately 142 million miles (228 million kilometers) from the Sun.
This difference in distance means that Earth is indeed the closer planet to the Sun when comparing the two. Both Earth and Mars are part of the inner solar system, but Earth is the third planet from the Sun, while Mars is the fourth.