Earth ,Venus and mars are much different from each other. there is much variation atmospheric properties. earth atmosphere consists of 75 % nitrogen and 21% oxygen and slight amount of Co2. Venus has 95% carbon dioxide and some sulfuric acid vapors. mars also consists of co2 but lesser amount than Venus. carbon dioxide is greenhouse gas. so, on Venus, temperature is up to 500 degrees. earth has max. 31 degrees and mars has 21 degrees. Earth and mars are placed in mainly habitable zone. Among these three planets, Venus has more atmospheric pressure. earth has intermediate between Venus and mars. whereas, mars has low atmospheric pressure.