Question

how atmosphere of earth is diffirent from venus and mars

Answer 1

The atmosphere on Earth constitutes 27% Oxygen, 78% Nitrogen and 0.03% Of carbon dioxide etc. Life is possible on Earth durle to presence of Oxygen
On the otger hand, The atmosphere of Mars and Venus constitutes of Mainly Carbon Dioxide!
Carbon dioxide is found about 95-97% Of atmosphere of Those Planets!
So, due to absencen of Oxygen, Life is not possible of Mars and Venus!

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.