Here are some key differences:
* Size: Earth is much larger than Mars.
* Atmosphere: Earth has a thick atmosphere that supports life, while Mars has a thin atmosphere, mostly composed of carbon dioxide.
* Water: Earth has abundant liquid water on its surface, while Mars has only frozen water and some evidence of ancient flowing water.
* Temperature: Earth's average temperature is much warmer than Mars.
* Life: Earth is teeming with life, while Mars has no known life forms.
While there are some similarities between the two planets (both have solid surfaces, rotate around the sun, and are within the "habitable zone"), the differences are significant enough to consider them separate and distinct planets.
