Question

how is the earth atmosphere different from that of Mars and venus

Answer 1

Earth's atmosphere is different from that if Venus and mars as they have large amount of CO2 and too much hotter as compared to earth temperature

Answer 2

$\implies$ Earth’s atmosphere is composed of various gases like oxygen, carbon dioxide, nitrogen, water vapour along with various gases in small quantities, hence making it a balanced composition which is more livable than other planets. Planets like Venus and Mars have more than 95% of carbon dioxide in the air making the existence of life impossible.